- This topic has 130 replies, 42 voices, and was last updated 12 years ago by molgrips.
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Diesel Vs Petrol
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mastiles_fanylionFree Member
carbon337 – Member
Dmf, turbo, egr, no more diesels for me. Sticking to Japanese petrols next time.
POSTED 3 HOURS AGO # REPORT-POSTOur Japanese petrol has been the most expensive car I have ever run (Mazda 3 2.0l). Most disappointing.
edoverheelsFree MemberVery impressed with everyones mpg figures. Mine seem much worse, whatever car I am driving.
bobloFree MemberI had one of those VAG 2.5 v6’s. 163bhp in an A6. I’d get ~34mpg ish combined and ~44mpg on a run. I don’t drive them hard and changed to the new 2.7 v6 again in an A6. I get ~42mpg combined and ~48mpg on a run.
Mrs Boblo has the 2.0l TDCI in a Focus. It gets ~55-57mpg on a run. It’s pre DPF but has had a DMF, Clutch, EGR and Alternator all at ~40k. It’s the first car we’ve had any of these bits on and I keep being told how unlucky I am…. yeah, me and my bank balance know this.
Our next cars will be petrol.
donsimonFree MemberWhat’s the 2.7 like to live with boblo? A couple of Le Mans Avants have vaught my eye.
mboyFree MemberIt’s a 2001 VW T4 Multivan, so how you are only getting those figures out of a car with a similar engine is a mystery to me ?
YAWN!
It’s quite a different engine actually. Yours is an inline 5 (essentially the 1.9 with and extra cylinder) I believe, not the V6 that is in my car. Fewer cylinders will naturally equate to slightly better mpg, and only driving the front wheels, not all 4, will also mean 15% better economy. And then again, going off the inboard computer will also massage figures by a further 15%…
My car is also mainly used for shorter runs these days, sub 20 miles. When I first got it I did more motorway journeys, and mpg was a good 2-3 better overall.
Anyway, that you get such high figures from a T4 with a 150bhp engine astounds me. I know someone with a T5 with a 1.9tdi in it (think its 100bhp but can’t remember), he can’t get more than 35mpg avg out of it despite never exceeding the speed limits anywhere and being very smooth with it. This is of course 35 ACTUAL mpg, not some forum warrior’s boasts about how good a driver they are based upon their own ego and massaging of figures for their own purpose.
Moving onto the subject of Japanese petrol cars briefly, oddly enough, reliable as most of them are, fuel economy never seems to have been a strong point with Jap cars. You’ll get much better economy from most European petrol models than you will from most of their Japanese equivalents.
DrPFull MemberMoving onto the subject of Japanese petrol cars briefly, oddly enough, reliable as most of them are, fuel economy never seems to have been a strong point with Jap cars. You’ll get much better economy from most European petrol models than you will from most of their Japanese equivalents.
I wonder if it’s due to the Japs being taxed on displacement, rather than CO2 production. Therefore, they milk the ‘most’ out of their engines (and why a lot of jap hot hatches are 2000cc – pretty smart getting 450bhp out of a coke bottle!), which will result in more fuel being burnt for a given displacement?
DrP
molgripsFree Membera DMF, Clutch, EGR and Alternator all at ~40k. It’s the first car we’ve had any of these bits on
I think you’ll find most of your other cars will have had clutches and alternators 🙂
Our next cars will be
petrolnot FordsFTFY
not some forum warrior’s boasts about how good a driver they are based upon their own ego and massaging of figures for their own purpose.
Can you just chill out? He’s relating experiences plain and simple. You seem to think we’re all having a go at you or something? I’m not reading aggression into any of these posts except yours, and possibly flow 🙂
mboyFree MemberMboy – how you been recently?
OK cheers, other than being skint and needing to either spend a load of money on my Audi, or sell it and buy something cheaper!
flowFree MemberI have always had VAG cars. When I sold the A3 TDI I thought I would look at other makes, problem was none of them drove as well, were as nice to be in etc.
Ended up buying the same car with a different engine, even the same colour 😆
aracerFree MemberThe car is also 11 years old
Mine’s over 12 – as mentioned above I still get 45+ (would probably get 50+ if I had as light a foot as some around here). That’s in a car with a quoted 1425kg kerb weight, so not hugely lighter than yours – clearly the 4wd is quite a hit though.
The thing is you’re not comparing like with like if you’re looking at standard petrol cars getting almost as good fuel consumption as you do, when the equivalent diesel would be better than 50mpg.
mboyFree Memberaracer, I was comparing like for like in terms of power output for cars made around that time, rather than engine size. Most 2L diesels peaked at about 110bhp back then, to get the 150bhp a 2L petrol made you needed a bigger engine. Call me old fashioned, but I like to know if I want to put my foot down, I can actually overtake something pretty quickly! I’ve owned a few underpowered cars in the past, it’s nice to have a bit in reserve.
You’re right about the 4wd though, it’s about a 15% effect according to the quoted figures for the fwd vs 4wd version of my car. Like I said though, I’, not actually complaining about my MPG.
bobloFree Memberdon simon – Member
What’s the 2.7 like to live with boblo? A couple of Le Mans Avants have vaught my eyeIt’s pretty good though I’d go for an auto as the manual cen be a bit snatchy on pull away. Otherwise, car is smooth, economical and in normal guise, 180bhp so plenty powerful enough. For long term ownership, it has chain driven cams rather than the belt replacement job required on the 2.5L@ 80k (IIRC). That’s an expensive job on the 2.5L.
I had mine chipped though and there’s loads of grunt whilst returning the mpg’s above. I didn’t fancy the 3.0L for the extra power as it only came in 4×4 mode and for 99.9999% of my driving, 4×4 is irrelevant.
I’d buy another though auto.
M6TTFFree MemberWhen I bought my Leon fr I test drove the petrol and the diesel back to back. I’ve never driven diesel before and had strong preconceptions of how horrible it would be. I was pleasantly surprised though. Yes it was noisy from start up, but after 10 mins it was fine unless you really gunned it. There was gob loads of pull when you put your foot down but it was all very short lived before requiring a gear. The only other thing I disliked was the length of time it takes for the heaters to start kicking out some decent heat. Seemed to be the same in all the diesels I’ve since driven too, down to the engine warm up time? In the end I decided I would have either depending on which car I found secondhand with the spec I wanted to become available first. Petrol won
molgripsFree MemberM6 – When was that? The all-then-nothing thing is a feature of a particular generation of VAG TDIs. I think Seat continued using them up until relatively recently, I think a 57 or 58 plate Altea I test drove had it. Later PD engines and common rail engines are not like that.
The heater thing is because more of the energy goes to powering the car, instead being wasted through the radiator 🙂 I read somewhere that when idling a petrol uses six times more fuel than a diesel. Maybe that’s why my car has electric heaters fitted so I get warm (ish) air straight away.
tonyg2003Full MemberI was reading about the new BMW 3 series (out next year) and BMW have put alot of work into their petrol engines this time around since they reckon that they will see a swing back to petrol purchasing over the car’s 7yr life cycle. All due to the difficulty / cost of making diesels meet stricter future emissions criteria.
molgripsFree Membersince they reckon that they will see a swing back to petrol purchasing
Yeah thanks to them and their swirl flaps!
It would be interesting.. more people buy petrol cars, demand for diesel drops, it gets cheaper…. VW might be annoyed with that since they’ve put so much effort into diesel. Toyota and Honda should be laughing with all their hybrid development. Petrol hybrid FTW.
M6TTFFree MemberMolgrips, yup 57 plate – pre common rail engine, couldn’t stretch to the revised model
mcbooFree MemberWe had a Volvo XC90 diesel for 6yrs, traded it in for another last year, it just ticks all the boxes. Only do 6k a year, starting to think it isnt worth paying the extra for diesel. Flip side is we’re a family of 5, couple of dogs, grandparents who visit, always ferrying other kids around…..7 seats is almost essential, dont know what else we could buy would do the job with a petrol engine.
mastiles_fanylionFree MemberI have a 175bhp diesel (Audi A6) and a 150bhp petrol (Mazda 3) – both manuals – so I think I have a couple of pretty comparable cars – the power to weight ratios must be pretty similar (although I have never checked).
The car I prefer to drive depends on the type of driving I am doing – for going up and down the motorway it is the diesel every time- it is just smooth and refined (although that may be more to do with the car itself, not the engine). But I still find the petrol engine to be far more responsive and (surprisingly) has more grunt at the lower end and is much more forgiving of bad gear choices – it just doesn’t have the dead spots the diesel has. So when I am zipping around town or wanting to get a bit ‘sporty’ I much prefer the petrol unit.
cookiesFull MemberI was getting 21/22MPG on a run but since the EGR blew coming back from France its only doing 18MPG. A new EGR and service is £900.
Why do EGR’s keep failing….
molgripsFree MemberSomethign else is probably wrong cookies. The EGR is just a valve. They get coked up if there’s a lot of smoke. So something could be causing soot and smoke.. Possibly short trips, possibly something else.
nealgloverFree Member… This is of course 35 ACTUAL mpg, not some forum warrior’s boasts about how good a driver they are based upon their own ego and massaging of figures for their own purpose.
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whats with the the sh!tty attitude ????
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I’m sorry you don’t like my MpG figures (or yours)….. but that’s what I get, why that would wind you up so much, and cause you to start throwing insults about is a mystery.(real figures worked out from how much fuel I put in and how many miles I do, as I need to do it for expenses)
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So you leave your @rsehole attitude for someone else and chill the **** out.5labFull MemberI think the low economy in this example is a factor of the car itself. the equivilent mondeo (st-tdci with 155bhp) has a combined rating of 46mpg. alternatively (for less money) you could probably just get a 130bhp one and chip it for the extra boost, which would give marginally more mpg (48 combined cycle). You’d probably also find that a 2wd car with 150bhp would be significantly more nippy than a 4wd 150bhp car, as its not got 15% additional drag that the 4wd entails (to compare it to the mondeo again (as its a good benchmark) – the 130bhp mondeo is as swift to 60 as the 155bhp audi despite the lack of traction)
Some petrols are now doing dmf to try to reduce the noise/vibration in the cabin, so the window for one without that tech is fairly narrow
there isn’t a definitive ‘cut off’ for a diesel being ‘worth having’. Diesels can have expensive repairs and cost more to buy – however they typically hold their value better, cost less to service (no spark plugs), cost less to tax (if a newer car) and use less fuel. There is a cutoff but you’d have to put a little spreadsheet together to figure out what is best. Independant warranty places (such as warrantydirect) don’t charge different amounts for covering a diesel vs a petrol (in the example of the mondeo, £393 each way) so there can’t be *that* much more in cost of repairs
martymacFull MemberOP
ive been wondering similar myself, as im thinking about changing my car next year, but the bottom line (for me) is this,
i have a 2l mondeo tdci, and the worst mpg i have had is 42 (booting it around town, air con on full blast)these are actual figures, my car doesnt have a trip computer.
my mate has a 2l petrol vectra (similar weight to the mondeo) and the BEST he has had is 45mpg, his average is 27(trip computer).
my average is around the 50mpg mark.
my car has done 144k with nothing other than routine service items/fair wear and tear ie brake discs etc.
i really dont know which way to swing next, probably a 2l petrol in slightly smaller car tbh.silvermattFree MemberI’m amazed at those Passat figures. I have 2.0TDi on 56 plate and only get 48 on a long run at 70mph. I’ve only ever seen 50 when its been heavy traffic and speed drops to 50-60 max. Its frustrating to hear 60+ figures from the same car. Its the first time I’ve bought VAG and right now I’m not convinced enough to stay with them next time. Have you chaps had injector swaps or any other issues? Do you run fuel additives like Millers or redex?
By the way my trip computer is very accurate. Can’t say how much exactly but on the few times I’ve measured it over a tank its been close enough for me to believe the mpg display.
molgripsFree MemberSilvermatt – cruise control?
Gradual creeping acceleration is your worst enemy, especially on motorways.
Oh, and buying scilica compound tyres (Nokian V in my case) added about 2mpg.
silvermattFree MemberI don’t use cruise control very often – typically only on long journeys and when its quiet. I generally drive on dual carriage ways when its busy so cc is a pain to use. Should using it make a significant increase in mpg? I’ve not noticed it make a difference to be honest.
Tyres are Kumho I’ve no idea what compound this is. I’d probably buy Falken next time just from my perceived value for money of this brand.
prezetFree MemberWell now I’m shitting it – just bought a 2006 Skoda Octavia Estate 1.9TDi… 😯
5labFull Memberwhat about your driving on DCs makes it hard to use cruise? are you braking? are you booting it? are your tyres pumped up? do you have the windows shut and aircon off? are you driving shortish (<10 mile) journeys from cold?
stumpy01Full Memberprezet – Member
Well now I’m shitting it – just bought a 2006 Skoda Octavia Estate 1.9TDi…Why are you “shitting it”?
I’ve got a Seat Ibiza with the same engine – 130bhp version. It’s done 173k miles. Only engine related issue was an intercooler pipe coming off. Turned out to be the wrong clip used from new to hold it on. It lasted 7 years or so, before failing. Replacement pipe & clip – £45 fitted.
Only other thing that failed unexpectedly was a wheel bearing at 38k miles, oh and the air con compressor died last year that cost £500 fitted.
I can get 55mpg out of it without really trying & at the moment in my ‘driving miss Daisy’ mood, I am getting closer to 60mpg average. Best from a full tank so far is high 63mpg (genuine calculated, not trip computer).prezetFree MemberWhy are you “shitting it”?
All this talk on here is a bit scary about diesel bits failing.
stumpy01Full Memberprezet – Member
All this talk on here is a bit scary about diesel bits failing.
I wouldn’t worry too much about it. So long as you have it regularly serviced, use the correct spec oil, don’t rag it from cold etc. it’ll (probably) be fine.
5labFull MemberI disagree. DMF, DPF and so on have no relation to whether a car is
a) serviced
b) ragged from cold
c) correct spec oilprezetFree MemberA silver lining, looks like the Octavia won’t have a DPF:
http://www.pistonheads.com/gassing/topic.asp?h=0&f=86&t=884383&mid=0
😛
silvermattFree MemberNo booting it or braking just trudling along with the flow. Its always busy bumper to bumper at 70 ish but it ebbs and flows which is why I don’t use cc. I’ll give it a go for the next few days and see if I notice a difference.
Tyres pumped up and checked regularly (they hardly lose any pressure over a month or more). Windows shut but aircon is generally on. I don’t tend to use the econ setting ever. Journey is 20 mile drive each way icluding quarter mile at each end on urban roads. In my mind it should be an decent commute for fuel efficiency.
mboyFree MemberI’m sorry you don’t like my MpG figures (or yours)….. but that’s what I get, why that would wind you up so much, and cause you to start throwing insults about is a mystery.
Have you read a word I’ve written?
I didn’t start this thread to have an mpg war. I’m not unhappy with my economy figure from my car, I chose that car for a reason. I’m actually (I’ll say it once again for those not paying attention) exceeding the manufacturers stated combined cycle figures, the first car I’ve had in ages that does.
My issue is with all the hidden costs that go with owning a diesel. With newer ones you’ve got the DPF’s and DMF’s and EGR’s that can fail, with an older car like mine it’s the diesel pump, the turbo and in my case the cams you’ve got to worry about wearing out.
I think the low economy in this example is a factor of the car itself. the equivilent mondeo (st-tdci with 155bhp) has a combined rating of 46mpg. alternatively (for less money) you could probably just get a 130bhp one and chip it for the extra boost, which would give marginally more mpg (48 combined cycle). You’d probably also find that a 2wd car with 150bhp would be significantly more nippy than a 4wd 150bhp car, as its not got 15% additional drag that the 4wd entails (to compare it to the mondeo again (as its a good benchmark) – the 130bhp mondeo is as swift to 60 as the 155bhp audi despite the lack of traction)
In fairness you’re talking about newer cars, with newer engine designs. My 2.5L V6 was around since about 1994, the cars you mention above have much more recent engine designs which will account for why they’re more efficient (as well as only being fwd) and can produce more power per litre.
GribsFull MemberWell now I’m shitting it – just bought a 2006 Skoda Octavia Estate 1.9TDi…
You’ve no need to as you’ve bought a car with a late 90’s diesel engine. Rough, but less to go wrong.
5labFull MemberNo booting it or braking just trudling along with the flow. Its always busy bumper to bumper at 70 ish but it ebbs and flows which is why I don’t use cc. I’ll give it a go for the next few days and see if I notice a difference.
Tyres pumped up and checked regularly (they hardly lose any pressure over a month or more). Windows shut but aircon is generally on. I don’t tend to use the econ setting ever. Journey is 20 mile drive each way icluding quarter mile at each end on urban roads. In my mind it should be an decent commute for fuel efficiency.
it could be your journey style. I can’t measure your aircon cost, but lets say it uses 500ml of fuel per hour. that’d be about 4mpg lost
for your jouney, you car is probably only running at its most efficient for 10 miles each way (50% of your travel). My personal car usage often involves journeys over 100 miles, probably average 50 miles. If I had the same car, it’d be at its most efficient for 80% of the time. if the car runs at 35mpg when cold but 60mpg when hot, this could be your difference
In fairness you’re talking about newer cars, with newer engine designs. My 2.5L V6 was around since about 1994, the cars you mention above have much more recent engine designs which will account for why they’re more efficient (as well as only being fwd) and can produce more power per litre.
completely agree, but in the same light, I don’t think its fair to compare that car to a modern petrol either. in the 90s you needed a similar engine to give you that power in petrol – the volvo 850 (non turbo) got about 160bhp from a 2.4l engine, and averaged ~25-30mpg.
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