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Petrol or diesel?
 

[Closed] Petrol or diesel?

 sbob
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squirrelking - Member

Sbob, you're taking the whole STW-dick thing to new levels.

No, telling me what I want and being wrong about it is being a dick.

If you want peak power delivery in a very tight rev range then go ahead

Plenty of power between 4,500 and 9,000rpm in my old Honda, does that sound tight to you?

As for the Grandad statement I wasn't slating Hondas, I was merely using them as a very good example of engines that require a lot of work to keep them at their peak power

Rubbish, you used the term "over use" and preceded the name Honda with "just". Not that it bothers me that you were "slating" Honda, merely that you then lie about it.

If you like low down torque and avoiding changing gear then good for you, I'm happy for you.
Don't tell me what I like however, because it is clear you are talking out of your bottom, and it hits a nerve.

Much like my joking pensioner comments, eh pops?
Am I right? 😉


 
Posted : 12/01/2015 2:41 pm
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Diesel's don't have the same gear ratios. In my car, at 70mph it does about 2krpm, my dad's petrol is about 2.8krpm. In both cases roughly half way through the rev range.

However my diesel comes on really stronly at about 1.2krpm, and in his case it does basically nothing until.. well.. 4k or so! His is a 1.6 Focus - it's smaller, slower and less economical.

Still struggling to see how his petrol is better to drive.

Of course, a big V8 petrol would be much better, but that's a premium engine and has costs to match - not a fair comparison with a 2.0 TDI.


 
Posted : 12/01/2015 2:42 pm
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So, right

If you were looking to buy a mid-ranged car for around £10k, around 5 years old 2010 - 2011, and reckon you'll keep the car for 5 years ish.

Is it wise to look for petrols, or is diesel still okay?

FWIW, I was looking at a 2.0 VW Scriocco GT. Diesel.


 
Posted : 12/01/2015 2:52 pm
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If you are buying used, you can choose your fuel and then adjust the age or mileage to suit your budget. So it depends on

a) preference
b) mileage vs fuel budget/desire to rape the planet
c) short/long trip ratio.


 
Posted : 12/01/2015 2:53 pm
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"You're probably right, though still felt like you were having to short shift and change gear every 2 seconds to keep the diesel up to speed."

what diesel was that ? sounds broken.


 
Posted : 12/01/2015 2:57 pm
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Sbob, if you don't understand the nuances of the English language I don't think you should be wading into a technical discussion. When I said "you want" I didn't literally mean YOU nor was I dictating a preference.

Not sure what I'm lying about either, I explained my reasoning for picking Honda (very familiar and involved with other owners), I may well have chosen something else but can't think of something that would have illustrated my point in the same way. Again, if you have difficulty grasping the English language I would get some remedial lessons before making a cock of yourself again.

Whatever your actual point was there were plenty of ways you could have said it civilly. That you chose to be a dick about it instead of being reasonable speaks volumes about you as a person. If you have nothing useful to add then please do yourself a favour and don't waste your time replying.


 
Posted : 12/01/2015 2:57 pm
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what diesel was that ? sounds broken.

Octavia VRS, both mapped and standard. In fact the mapped cars managed to feel worse as they got through what few revs they had even quicker. Pretty sure they weren't all broken but felt that way in direct comparison to the petrol equivalent.

I do think diesels have their place and can be great cars, just not in that car. 330d/335d for example felt a far better all round package.*

*added as I'm not anti diesel cars in general


 
Posted : 12/01/2015 3:00 pm
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Octavia VRS, both mapped and standard.

What year? Older PD engines before.. er.. 2004-5 ish had mechanical PD injectors and they were definitely narrow power banded.

However they were still fast enough, if you knew how to drive them. And the huge torque in that narrow band was actually brilliant for driving on windy roads. My Ibiza felt far far quicker than my dad's Fiesta (and was far more fun to drive) despite the same bhp.


 
Posted : 12/01/2015 3:05 pm
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oh i agree - why would you want a diesel performance car.

recipe is something like take 1 x 2 litre engine bolt on big turbo.

result is not very nice to drive.


 
Posted : 12/01/2015 3:08 pm
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And the next person who posts up dyno graphs of engine speed vs power or torque gets a dirty look.

Dammit!

Of course, a big V8 petrol would be much better, but that's a premium engine and has costs to match - not a fair comparison with a 2.0 TDI.

How about a 2.0TDI and a 2.0T petrol?

Compare a Golf GTD to a Golf GTI
The diesel has more torque than the petrol but never gets near it in terms of performance

2 reasons:
Firstly torque is meaningless without considering gear ratios the petrol driver is effectively 1-2 gears lower than the diesel driver.

Secondly power is everything!


 
Posted : 12/01/2015 3:08 pm
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oh i agree - why would you want a diesel performance car.

Depends on the car. Lotus Elise - no. Audi A5 3.0 V6 TDI yes. BMW 535d - yes.

More than one way to enjoy driving.


 
Posted : 12/01/2015 3:09 pm
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How about a 2.0TDI and a 2.0T petrol?

Compare a Golf GTD to a Golf GTI

Well getting like for like depends on what you compare. Comparing similar displacement doesn't make as much sense as you'd think, because the engines work differently.

Comparing the GTI and GTD makes more sense though overall. Both essentialy the same type of car, and they have different pros and cons. GTI is for those who want the most speed, GTD for those who want plenty of speed but still economy.

A good comparison I'd say is bhp. I've compared a 105bhp diesel with a 105bhp NA petrol and there is absolutely no way in which such a small petrol is better.

With say a 150bhp turbo diesel and turbo petrol it's closer - but the diesel gets far better economy.

And comparing like for like on economy - a diesel will be vastly better.


 
Posted : 12/01/2015 3:13 pm
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molgrips

A good comparison I'd say is bhp. I've compared a 105bhp diesel with a 105bhp NA petrol and there is absolutely no way in which such a small petrol is better.

Is that a 105bhp tdi vs a 105na petrol? How did the torque figures compare?


 
Posted : 12/01/2015 3:15 pm
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Audi A5 3.0 V6 TDI yes. BMW 535d

Cruisers.

like comparing a harley to a gsxr imo.

Gimmie the audi or the beemer any day for a day to day car - but id rather the 2.0d in either ill be honest.


 
Posted : 12/01/2015 3:16 pm
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Depends on the car. Lotus Elise - no. Audi A5 3.0 V6 TDI yes. BMW 535d - yes.

There's a guy who lives near me with a brand new Audi TT...in diesel flavour...for the weekend. He drives a petrol golf to work!

I can't get my head round spending £30k+ on a sporty(ish) car like the TT and then try to save a few quid on fuel? Maybe he just really likes how the torque makes the road come alive?


 
Posted : 12/01/2015 3:18 pm
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I can't get my head round spending £30k+ on a sporty(ish) car like the TT and then try to save a few quid on fuel?

Environmental conscience?

Anyway it's not just a few quid, is it? It could be a couple of thousand quid over say 200k miles ( not done sums) and that pays for the stero upgrade, a DSG, the built in satnav or some other expensive options.


 
Posted : 12/01/2015 3:19 pm
 sbob
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Woah there SK!
Maybe the light-heartedness of my initial reply was too subtle for you to understand, hence why you waded in with the insults. 💡

Maybe you should take my car for a spin; it always brings a smile with its cheeky looks and flower graphics. 8)


 
Posted : 12/01/2015 3:23 pm
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Environmental conscience?

Anyway it's not just a few quid, is it? It could be a couple of thousand quid over say 200k miles ( not done sums) and that pays for the stero upgrade, a DSG, the built in satnav or some other expensive options.

Since when was having a second, sports car with a diesel engine, environmentally friendly? 🙂

Also, what are the chances that he'll be sticking 200k miles (ie almost the distance to the moon) on a weekend car?

(it would take him 20 years of sticking 200 miles on it every weekend to hit that figure!)


 
Posted : 12/01/2015 3:26 pm
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My car always gives me a smile when I return to it in failing light after a long cold wet ride in the mountains... 🙂


 
Posted : 12/01/2015 3:27 pm
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Ah I didn't see the 'weekend' part.

Still - why not ask him? Perhaps he preferred the drive? Perhaps his weekends involve driving to Edinburgh or something?


 
Posted : 12/01/2015 3:28 pm
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A good comparison I'd say is bhp. I've compared a 105bhp diesel with a 105bhp NA petrol and there is absolutely no way in which such a small petrol is better.

I agree, but that's also argument of forced induction versus NA.

How about the 1.8TSI in the new Leon FR (180bhp) versus the Golf GTD (184bhp)

The Leon is giving away a huge amount of torque (250Nm versus 380nm) and yet the acceleration of the two cars is very similar (shorter gears and a bigger rev range make up for the comparitive lack of torque)

Now try finding a small diesel that compares well to the 1.0L Ford Ecoboost


 
Posted : 12/01/2015 3:39 pm
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How about the 1.8TSI in the new Leon FR (180bhp) versus the Golf GTD (184bhp)

It'd be an interesting comparison. Probably come down to preference and what you want out of it.

Now try finding a small diesel that compares well to the 1.0L Ford Ecoboost

It'd be a 1.6 bluemotion type thing. They are quite driveable by all accounts.


 
Posted : 12/01/2015 3:44 pm
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Ah, sod it. I'm back in (bored at work)

Depends on the car. Lotus Elise - no. Audi A5 3.0 V6 TDI yes. BMW 535d - yes.

But a petrol version is even better - the 535 is at least accompanied by a sonorous soundtrack. The BMW X35's a very fast and very competent, but to me offer very little else.

Now, going off topic a bit...

With regards to cars doing 200k, I can't see many modern cars getting that far without serious money thrown at them at some point - BMW's seem faiurly prone to eating turbos plus HPF issues that are pricey. There are a fair few guys at work who have had Passat's etc needing turbo replacements by 70k. The 7 speed DSG box isn't known to be the most reliable thing.

The drive for ever greater ecomony and lower emissions does seem to be leaving us with cars that will throw up some big bills early on. I have a friend who had a 540 that went on to 275k befoure rust killed it with very little money having to be spent on it, but that was a massively understressed, lazt engine.


 
Posted : 12/01/2015 3:52 pm
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I've had all sorts of petrol and diesel cars. I have a dinosaur of a 3.2 V6 in my Golf at the moment, which does 25mpg overall and cracks 35 if I drive like Miss Daisy.

That's almost the same on fuel as the supposedly more fuel efficient 2.0T lump I had in my old S3. Big NA is also the most smooth and luxuriant driving experience I've come across. The R32 will even accelerate reasonably at just idle speeds (i.e. not using throttle), which is something I've previously only been able to do with diesels.

But the main thing I want to add to this is...

Depreciation!

I only do around 8-9k miles per year; and only 5k of those are not on business. Fuel and VED costs do need to be considered, but - depending on what your budget is and what you buy - depreciation is a much larger cost in my experience.


 
Posted : 12/01/2015 3:54 pm
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My 2p:

Firstly I like the way diesels drive, some of my mates won't touch the dark stuff - "it's horrible to drive" and sure enough they drive them like a petrol - they floor it straight through the power band, onto the redline next gear barely sees the powerband at all - lots of noise, revs, soot, very little forward motion and 20mpg. Drive like a diesel though and they do that whole 'inoffensive pace' thing really well - they're also not slow - real world stuff like 30-60 joining a motorway they're faster than the equivalent petrol and more relaxing to drive unless you're city driving IMO.

After 10 years of diesels I find most petrol cars harsh and gutless.

In regards to costs - there is some formula that was dreamt up by some petrol head (on Pistonheads I think) who said that you need to do 25-30k miles a year to make it work - I don't see how Diesel is 6% more expensive than Petrol - even the latest tiny turbo petrol engines aren't anywhere near that close to diesel - certainly not 'in the real world' truth is, even the famous 3 pot Ecoboost isn't great on fuel unless you nurse it everywhere - and sorry, the diesel denyers can point to supposed reliability issues with diesels - but the technology they use the make them more flexible which supposedly fails expensively all the time is the very same technology they're using to make a tiny petrol efficient.

No to me it's the same formula as it's always been short trips or lots of stop-start driving - petrol, longer trips diesel.


 
Posted : 12/01/2015 3:59 pm
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I only do around 8-9k miles per year; and only 5k of those are not on business. Fuel and VED costs do need to be considered, but - depending on what your budget is and what you buy - depreciation is a much larger cost in my experience.

And works in your favour when buying a car second hand, especially in this country where people are obsessed with fuel ecomony and Co2.

In regards to costs - there is some formula that was dreamt up by some petrol head (on Pistonheads I think) who said that you need to do 25-30k miles a year to make it work - I don't see how Diesel is 6% more expensive than Petrol

I think that forumla is taking into account the likes of purchase price plus servicing. In some cases the latter is more expensive on dervs than petrols - local BM indy charges more to service a 330d than a 330 petrol.

even the famous 3 pot Ecoboost isn't great on fuel unless you nurse it everywhere

In my experience, Ford's economy claims are even greater works of fiction than those of other manufacturers. Even driving like miss daisy on lots of long motorway trips (suited to diesels) mine is way off the claimed.

If I apply the same reduction on ecomomy to the petrols that I am looking at, then it won't cost me any more to fuel and the BIK is lower and a lower list price. Stacks up for me.


 
Posted : 12/01/2015 4:26 pm
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if I drive like Miss Daisy.

Miss Daisy does not drive, she has a chauffeur.

I think that forumla is taking into account the likes of purchase price plus servicing.

Yes, it assumes buying from new where you pay more. Second hand you (can) pick the price point and choose the age, so diesel need not cost more to buy.

local BM indy charges more to service a 330d than a 330 petrol.

I wonder why? The expensive items in a diesel aren't service items.


 
Posted : 12/01/2015 5:08 pm
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oil and oil filter/fuel filter are more expensive on most turbo diesels.

but not a huge amount.

the void between the cost of a used petrol vs used diesel is what makes the biggest difference for me and could drive me back into a petrol.

i honestly dont know what ill buy once my 1.9 8v diesels bite the dust - get taxed off the planet.


 
Posted : 12/01/2015 5:12 pm
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i honestly dont know what ill buy once my 1.9 8v diesels bite the dust

Another diesel? Modern ones aren't the disasters you appear to think.


 
Posted : 12/01/2015 5:21 pm
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About 10 years ago I bought a Ford Focus. I sat down and worked out, doing an average of 12k a year mainly on motorways and A roads, how much a petrol and a diesel would cost to run.

Factoring in tax, fuel cost difference, service intervals (which to be fair is now not so important as more modern diesels are looking at 10k gaps) and every other expense I could think of, I did my sums.

Over a year the difference was something daft like £10.

I went for the petrol because it was more fun to drive.


 
Posted : 12/01/2015 5:23 pm
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they are at the age i buy em......


 
Posted : 12/01/2015 5:25 pm
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(which to be fair is now not so important as more modern diesels are looking at 10k gaps)

When did diesels have shorter service intervals?

I'm on variable intervals, I get about 17k between lights.


 
Posted : 12/01/2015 5:26 pm
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We have a '95 Mazda Bongo with a Ford/Mazda 2.5 diesel turbo lump (same as the Ford Ranger) - recommended 4k service intervals.

The mk1 diesel Focuses (Foci?) I was looking at had an interval of about 6k, compared to an 8/10k petrol interval, and petrol services and spares were cheaper.

I'm potentially picking up a new-ish 2009 Octavia diesel this week - service interval is 10k.

That's my basis for comparison. 🙂


 
Posted : 12/01/2015 5:33 pm
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trail_rat - Member

they are at the age i buy em......

Post of the thread! 😆

My diesel doesn't seem massively more expensive to service than my previous petrol. I think the oil is a bit more expensive - PD oil and more of it, than the engine in the petrol Fiesta that went before it.

My current car supposedly requires services every 10k miles, but I've stretched it out to 15k miles as 99% of my miles are sat at a steady speed on A roads and it's a decent size, unstressed engine in a small car. I've done that for over 100k miles now and it doesn't seem to have suffered any ill effects.

My Wife's previous Peugeot 308 1.6 was a god awful car, but had a 20k mile service interval which impressed me (about the only thing that did about that car).

Anyway, have we come to a conclusion yet?
Just to stick my oar in - for the mileage the OP is considering it would be diesel for me all the way. I wouldn't want to be covering those miles in a high revving, fizzy petrol engine. Fine for a weekend car or lower mileage.....but diesel would cover those miles in a more relaxed fashion - I find cars that are buzzing away at 3k+rpm on the motorway very tiring.


 
Posted : 12/01/2015 5:40 pm
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When did diesels have shorter service intervals?

I'm on variable intervals, I get about 17k between lights.

They all seem the same these days - apart from Ford who still seem to use short service intervals. My Ford is in every 12k but my MINI's and BM's in the past have been up to around 18k (depedning on how they were driven). Only VAG seem to offer standard (10k or 1 year) or the long life.

Just to stick my oar in - for the mileage the OP is considering it would be diesel for me all the way. I wouldn't want to be covering those miles in a high revving, fizzy petrol engine. Fine for a weekend car or lower mileage.....but diesel would cover those miles in a more relaxed fashion - I find cars that are buzzing away at 3k+rpm on the motorway very tiring.

But I'm often surpised how bad NVH levels can be in diesels at motorway speeds - my Grandad has just bought a new Passat and I thought it was quite gruff at motorway speeds. That may be down to the fact that it's one of the smaller, lower powered versions.

It's not just petrol cars that are going down in capacity - a 1.6 seems pretty diddy for a car like a Passat.


 
Posted : 12/01/2015 5:53 pm
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I wouldn't want to be covering those miles in a high revving, fizzy petrol engine. Fine for a weekend car or lower mileage.....but diesel would cover those miles in a more relaxed fashion - I find cars that are buzzing away at 3k+rpm on the motorway very tiring.

My petrol revs to 8k and sits at 1,800 at 70mph. Hardly fizzing away and not a big engine.


 
Posted : 12/01/2015 6:34 pm
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But I'm often surpised how bad NVH levels can be in diesels at motorway speeds

Funny. My Passat (older 2.0 TDI) is very noisy at low speed but very quiet on motorway. And my dad's car is almost silent at low speeds but because it's near 3krpm on the motorway it's actually a lot noisier.

a 1.6 seems pretty diddy for a car like a Passat.

A diesel gets it's power from more air and more fuel. But because it's compresison ignition you can simply ram more pressurised air into the cylinder without worrying too much. So a bigger turbo and smaller cylinders is the same (actually slightly better due to higher pressure and there being more air molecules closer to the fuel droplets) as smaller turbo and bigger cylinder. Same amount of air, same amount of fuel = same power. Well.. up to a point.


 
Posted : 12/01/2015 6:41 pm
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peterfile - Member

My petrol revs to 8k and sits at 1,800 at 70mph. Hardly fizzing away and not a big engine.

What's that then? I've never been in a petrol that revs that low at 70mph.

Most petrols I've ever been in sit at around 3k rpm at 70. My Wife's 308 was even higher; about 3.5krpm and a mates Corolla T-Sport which had about 190bhp say at around 3.5-4k rpm I seem to remember.
My Ibiza is at around 1800rpm at 70 - 1.9 TDi with 130bhp.


 
Posted : 12/01/2015 9:19 pm
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stumpy, my mistake...I was reading figures for the auto.

I checked mine this morning and it's 2,000 rpm at 70mph (so not too far off though!), and engine noise is barely perceptible at that speed unless accelerating.

It's the B8 2.0 TFSI engine, which seems to be highly rated (although I know nothing about engines other than info I can find online!).

My brim to brim for that last 500 mile trip worked out at 39.5 mpg, that's with winter tyres on, not driving like an idiot, but no cruise.


 
Posted : 13/01/2015 8:36 am
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What kind of driving peter? As said I'm interested in that engine for when I next change the Passat. In about 2025 🙂


 
Posted : 13/01/2015 9:13 am
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Mol, my 16 mile commute is a few miles of residential and city driving, with the rest being motorway driving at 40-60 mph, generally in medium traffic. I get about 38-40 mpg.

Sitting at 75 on a long motorway journey will return about 40 mpg.

30 mins of congested city centre driving doesn't seem to dip below 26/27 mpg (on the DIS, but it isn't too far off my brim to brim calcs though).

What is most interesting (for me anyway) is that the mpg doesn't seem to take too much of a hit when you're on something a bit more twisty or are up and down the gears. Up the A82 for example...100 miles of a mixture of city, 30mph twisty stuff along the loch and then loads of quick and hilly A road with a few overtakes...making no attempt whatsoever to drive economically...I seem to get about 36mpg.

It seems pretty good for a car that will get to 60 in 6.5 seconds and has plenty of power for A road overtakes.

It also sounds quite nice for a relatively small engine.

The torque (that everyone who likes diesels bangs on about) is about the same as in the 2.0 diesel.


 
Posted : 13/01/2015 9:41 am
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Still does not compare that well to the ease with which I can beat 50mpg for a tank though on my diesel. I can get 48 ish on twisties with no effort, and Around 60 with grey effort. On motorways I can easily beat 60 in the summertime. And that's in a pre-bluemotion car.

I would like to try one of these cars to see how well I can do.


 
Posted : 13/01/2015 9:43 am
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Well aye, obviously a diesel engine of comparable size will beat a petrol in pure mpg terms.

But, as I mentioned earlier, the diesel version of my car was more expensive to buy and at 15,000 miles per year I'd only be saving £300-400 a year in fuel, so it would take me years to make the diesel cheaper.

I focus on the cost to me to run over the course of ownership, rather than per journey or per month etc. There wasn't anything in it overall between the two cars and I far preferred driving the petrol, it suited me better. It's nice to be able to take cost out of the equation and just choose your favourite.


 
Posted : 13/01/2015 9:47 am
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It's the B8 2.0 TFSI engine, which seems to be highly rated (although I know nothing about engines other than info I can find online!).

They are good engines but let me know how you get on when you rev it to 8000rpm


 
Posted : 13/01/2015 9:49 am
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I'm more concerned about environmental impact (but also cost*), and I'm thinking of petrol because diesel is dirty stuff and it also can cost more CO2 to produce although this isn't well known.

* having said that a diesel won't cost me more than a petrol - it'll just be older or higher mileage.

They are good engines but let me know how you get on when you rev it to 8000rpm

Why would he want to do that?


 
Posted : 13/01/2015 9:53 am
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