the point is that the Prius is a big car

Not that old chestnut again. In terms of interior space it's certainly not a big car. If I drove at the speed limit I'd get pretty close (if not better) your figures in what is really a large car – can certainly manage 50+mpg with a light right foot. Oh, that's a 10 year old large car.

That's not true with fuel injected cars, and it's never been true of diesels.

LOL

You SURE of that?

On some of the VERY latest diesels, yeah you're right. But on just about anything else, regardless of whether or not it's fuel injected, the engine is still burning a very small amount of fuel (approx the same amount as if it were sat idling).

Molgrips, your right he didn't get 80 mpg from an old passat on average, he only manages about 77-8mpg then. :p
He can get the 80+ on a trip from Nailsworth to Gloucestershire airport, but can't do as well on the way back.
That Prius planetary gear setup is nothing new, and I'm not being funny. That setup, albeit with 3 planetary gears (instead of 4 and a multiplate clutch pack) is what connects the rear wheels of my Cavalier 4×4 with the front axle.

You SURE of that?

On some of the VERY latest diesels, yeah you're right. But on just about anything else, regardless of whether or not it's fuel injected, the engine is still burning a very small amount of fuel (approx the same amount as if it were sat idling).
Well I'm sure – on overrun the fuel injection will shut off.

Oh, almost forgot 😆 😆

I get 53mpg on tank from my 1.7 non-turbo diesel 1998 Vauxhall Combo, just shows that the prius is nothing remarkable. Though my van won't do more than 88mph downhill lol.

Agreed. Some creative maths here methinks. I've now got an N plate Golf (no company car when you're on the dole! ) with the same 1.9TDi engine. It's a great engine for what it is, remarkable in fact when you consider at the time it came out all other diesels were crap underpowered junk with nowhere near the economy. But in my Golf, a lighter car than the Passat, the absolute best I've achieved when driving very sensibly is about 56mpg out of a tankful. More normally I achieve between 48 and 52mpg depending on whether or not that's more town or open road driving.

You have to realize, that the driver in questions has spent years perfecting a technique of engine off coasting, shutting the engine off at lights and absolutely no change in throttle travel. I've been a passenger on several occasions, and I'm not suprised, its quite scary his approaches into roundabouts etc 😆

Well I'm sure – on overrun the fuel injection will shut off.

LOL

[Tommy Cooper Impression Voice]"Just Like That!"[/Tommy Cooper Impression Voice]

Just shuts off does it? What tells it to start again? 😉

It's the way a car is mapped… Some very modern cars are mapped so that the engine is indeed burning no fuel under deceleration (which is still less efficient than an electric motor actually recharging a battery, but nuff said there!). Only some very modern cars though.

I'd absolutely LOVE to hear how a diesel engine with Mechanical fuel injection doesn't provide fuel to the engine under deceleration still. Otherwise it would never tick over! 😕

You have to realize, that the driver in questions has spent years perfecting a technique of engine off coasting, shutting the engine off at lights and absolutely no change in throttle travel.

OK fair enough, and I suppose the route that you described takes in a big section of downhill the one way too, hence why he can't manage the same MPG on the return route.

In terms of interior space it's certainly not a big car

It's bigger than a Golf – as big as an older Passat. You talk like I've never been in one.

You SURE of that?

Yes. The forward motion of the car is what keeps the engine turning. Why inject fuel?

That Prius planetary gear setup is nothing new, and I'm not being funny

Planetary gears have been around for years. The use of that setup with two motor/generators for driving a car is new. The MkI Prius was the first car to have it – 1997.

As for the 80mpg story – he must've been driving like a snail. Anyone else who's driven one of those cars (and there are a lot of us about) can tell you that's not practical for normal driving ie not stupidly slowly.

In my other car, a Passat 2.0 TDI, I have got 54mpg on a long 70mph run on summer diesel, but the long term average since September is about 42 or so. What's interesting though is that that can drop to the low 30s when you get stuck in traffic. The Prius handles traffic way way better, which is where we came in isn't it? Suitability of different drivetrains for different conditions?

Yes. The forward motion of the car is what keeps the engine turning. Why inject fuel?

Totally, why inject fuel indeed…

Only something that has been addressed MUCH more recently than you might think though!

I'd absolutely LOVE to hear how a diesel engine with Mechanical fuel injection doesn't provide fuel to the engine under deceleration still. Otherwise it would never tick over!

You really want me to dig out the schematics for the Bosch VE pump? From memory there's a governer that shifts the control collar to provide more fuel to the plunger when rotation speed drops below a certain amount. That's how it idles when you have your foot off the pedal, and also why it uses no fuel when the forward motion of the car is spinning the engine and hence governer and your foot's off the pedal.

http://home.comcast.net/~vwgtd/ve_174.jpg

You have to realize, that the driver in questions has spent years perfecting a technique of engine off coasting, shutting the engine off at lights and absolutely no change in throttle travel. I've been a passenger on several occasions, and I'm not suprised, its quite scary his approaches into roundabouts etc

So he's an ultra-miling tw*t then? The record fuel economy for my Prius model was 112mpg averaged over a whole tank, using a coast and burn stragety on empty flat rural roads. Not really a very useful thing to be able to boast about is it?

As for the 80mpg story – he must've been driving like a snail. Anyone else who's driven one of those cars (and there are a lot of us about) can tell you that's not practical for normal driving ie not stupidly slowly

No driving like a snail, coast as fast as you like, and you'd be surprised how far you can coast if you really put your mind to it. He'll still achieve 75+ on average on a tank. He will stick to around 55mph, but only in suitable areas and I say 'around' because he doesn't lift or press the throttle harder for to keep the speed the same, just flat level.

So he's an ultra-miling tw*t then? The record fuel economy for my Prius model was 112mpg averaged over a whole tank, using a coast and burn stragety on empty flat rural roads. Not really a very useful thing to be able to boast about is it?

Why isn't a useful thing to boast about? Why buy a Prius if its not about the 'not burning precious natural resources'? He's got a 15 year old car, its not digging more raw materials out for a new one every 3 years and its achieving a approx 75% improvement in fuel economy. Way I see it, thats far more cleaner and greener than your Prius will ever be.

Bored now.

How about a diesel hybrid, 1960's style?

Old tech

I think we should move to the 'Flintstones' model.

However you do it, moving a ton of metal at 60mph needs too much energy
Stick to your bike ❗

Why isn't a useful thing to boast about?

Cos it's not practical to drive that way, and it's not really safe either. There's a load I could do in my car to increase MPG, and if I was prepared to drive erratically and get in other drivers' way I could increase it much more.

Whilst we're on about ideal journeys, I once got 78mpg coming from my sister's in Bucknell, Shropshire to Ludlow. It's up a steep hill then down a very long gradual one, and since the Prius automatically coasts under light throttle I got good results. Also got a similar figure driving to town from my house, 5 miles or so, slightly downhill, when there was no traffic.

Sticking to your bike is best naturally, as long as you don't need to move anyone else around and you don't need to travel hundreds of miles away from railway stations 🙂

He's got a 15 year old car, its not digging more raw materials out for a new one every 3 years and its achieving a approx 75% improvement in fuel economy. Way I see it, thats far more cleaner and greener than your Prius will ever be.

That car was new once mate. How do you know how long I'm keeping my Prius for? Being a bit presumptious are't you?

Also, bear in mind that his diesel produces more CO2 than my petrol, so 60mpg of petrol is worth about 70 ish mpg of diesel in terms of carbon emissions. Also his old diesel produces a hell of a lot of NOx which my petrol doesn't, not to mention all the particulates since he has no filter. So it's not significantly greener in terms of emissions really. And in 15 years time maybe I can boast the same abotu my old Prius..?

How do you know how long I'm keeping my Prius for?

15 years? That would be far longer than normal for a Prius owner (can I point out that we're not specifically having a go at you – unlike many Prius owners you do appear to have a clue). Of course despite some people getting a new car every 3 years, that doesn't mean cars get scrapped after 3 years, however it would seem that scrapping after 10 years is now the done thing…

I don't see what is inherently unsafe about ultra-miling either (assuming you're not into tricks like drafting 3ft behind HGVs).

Hyper miling is only practical if you have empty roads. It would really get up other drivers noses if you did it in traffic. Thereby leading to great rage perhaps and more agressive overtaking etc although the responsibility for keeping calm lies with every driver not the thing annoying them. So I guess unsafe isn't the right word, but impractical for sure. For starters, if everyone did it it wouldn't work.

As for normal Prius owners – I don't know if there's a 'type' for Prius owners. If there is, round by us it's old folk since they seem to be the most common drivers I see. I guess the reason you only see newer Priuses is because they've only been out (in a decent form) since 2003, and they only started selling in reasonable numbers in 2005 ish. Check back in 2015 maybe 🙂

On the other hand, changing cars every year isn't really related to what car you buy, is it? I mean I'm sure people did this before hybrids were invented… So I suppose if you are going to change your car frequently it might as well be an economical one.

As for scrapping older cars, this is an intersting topic. Where my wife's from in the States cars are kept far longer than they are here. Maybe because used car prices are very high, which is odd because new car prices are quite low. Certainly cars that would be junked here would be worth several thousand there; you need a good few thousand to get anything decent to drive and if you only have say one thousand you get a complete wreck. It could be something to do with them having no MOT requirement tho, cos that's usaully what kills cars here. The market for spares and tools to fix your own cars is high over there, and there are plenty of mechanics willing to work on old cars unlike here where they tend to just fob you off with the excuse that it's only old rubbish.

It is true then that pepole buying new cars frequently trickles down the market with the result that most people are now driving a modern efficient safe car, but that in turn means more perfectly viable cars ending up on the scrap heap. This has to have good implications for safety and tailpipe emissions.. but not necessarily manufacturing. Then again, that leads on to the debate about traditional economic growth vs eco friendlyness – whether or not the two are mutually exclusive, as I suspect they are.

Then again, that leads on to the debate about traditional economic growth vs eco friendlyness – whether or not the two are mutually exclusive, as I suspect they are.

correct.

<<prius is nothing remarkable.>>

yer i had one on hire and got the mpg down to 26mpg! lol – only seems efficent at 55mph – fully loaded and flat out you would be better of in a decent diesel – even my dads 4.2 twin turbo Audi A8 will for 40mpg on a run…

anyhow a good thing out electric cars is that whilst there are issues about moving emissions and transmision losses in the nationa grid they do remove emissions from towns and to large point sources such as power stations – easier to abate one large source than lots of little ones.

addtionally as district/micro generation picks up then transmission gris losses will be reduced.

nothing is clear cut in the environment game!

Maybe for now TJ, but people are trying to find better paths:

Prosperity without Growth
Economics for a Finite Planet
http://www.earthscan.co.uk/ProsperityWithoutGrowth/tabid/102098/Default.aspx

What annoyed me about the scrappage scheme was the complete lack of measurement. Why didn't they insist the new car must be at least, say 15mpg better than your old car?

<<What annoyed me about the scrappage scheme was the complete lack of measurement. Why didn't they insist the new car must be at least, say 15mpg better than your old car? >>

yep too right – poor use of government instrument.

So are they greener then, there seems to be much umming and ahhing here? I'm the OP and I'm none the wiser.

It seems that were we using renewables for all our electricity then electric cars are viable but as it stands today there is very little environmental benefit to going electric. A conventional deisel built for low fuel consumption is the way to go.

If I, for example, wanted a new car next year waiting for an uber tricky electric hybrid doo dad to come out is pretty pointless.

Joolsburger – not significantly if at all is the answer.

It really depends on what you are wanting to achieve. Better air quality in towns – good for that. Reduced greenhouse gas emmisions in total – not so good.

If you are wanting a "green car" and no such thing actually exists then a small light car with a long life and an economical engine is as good a bet as any – imo

What annoyed me about the scrappage scheme was the complete lack of measurement. Why didn't they insist the new car must be at least, say 15mpg better than your old car?

Well to be fair, it would seem that the vast majority of new cars bought under this scheme were cheap small cars which are relatively economical (doesn't make so much sense saving £2k off a £20k car as off a £8k car, where it makes a brand new car just as cheap as a s/h one).

You are making the mistake though of assuming the scrappage scheme has anything to do with the environment – is all about economic stimulus, and see comment above from molgrips!

Joolsburger, I think you sum it up pretty well.
Here and now in 2010, small light economical cars are the best bet for emissions (thats why I drive an Audi A2).
However as a country we WILL have lots of wind power over the next decade, and using the battery storage of electric cars will be part of that energy solution. My own thought is that even if in the short term the electricity comes from coal or gas then thats the price that has to be paid to generate the market for electric cars.

Small cars are best – of course, some folk need something larger when they have kids and whatnot.

fully loaded and flat out you would be better of in a decent diesel

Not really. Like I say I get 60mpg in the summer time at the speed limit, goes down to 52-54 on an 80mph run down the M4. At the time I bought the car there was nothing in diesel that could compete with that, for a similar size. Now a bluemotion Passat can beat it in terms of mpg but produce more CO2. Then again the new Prius is better still.

Molgrips – no matter how you try to justify it to yourself you know you are wrong. The prius simply is not a green option. It is designed for places where you get tax breaks for zero tailpipe emissions. Its lifetime environmental footprint is poor.

You may want a largeish luxury car. You do not need one. A fiat panda would do all; the practical tasks just as well.

addtionally as district/micro generation picks up then transmission gris losses will be reduced

Sadly not quite as simple as that. It may make them go up or down depending on the generation penetration in different areas. We are already exporting distributed generation (11kV or LV connected stuff) on to the supergrid (National Grid to you) and transporting the power off to other areas – in the company for which I work as the design manager, so that's first hand experience. Why not use it locally? Because it is a generation rich area, not load rich. And that sadly leads to more "grid" losses. Other places it does save losses.

The prius simply is not a green option. It is designed for places where you get tax breaks for zero tailpipe emissions.

I don't believe so. Wanna show me the unbiased scientific studies so I can change my mind?

PS they are still selling fast in the US and there are no longer any tax breaks. They are selling based on high fuel economy.

As for needing a big car, well we don't need a car at all do we if you're going to split hairs. You also don't need a computer to come on STW, how green is that? Your house doens't need heating either for that matter. You could live off-grid with super insulation and solar powered LED lighting. But you don't, do you? Why not?

When I bought that car the Prius was the greenest car that I could fit me, my wife and my biking stuff in. According to the Green Car Congress website and some other stuff I'd read (which included ashes to ashes energy costs).

Also, check this out. The factory that makes Priuses gets half its electricity from solar power.

PS they are still selling fast in the US and there are no longer any tax breaks. They are selling based on high fuel economy.

Not because of the "looking like you're being green" factor?

The thing is, whilst the economy on runs might be very good, it's not really all that special – I can get 50mpg at 80 with something rather bigger than yours (and 10 years old). Why would you expect otherwise given all the clever electric stuff is just so much dead weight on such a run, and the only reason for the slightly better figures is very careful tweaking of aero, engine performance etc.

Aracer – so what? Prius CO2 emissions are lower than any other car, including your ten year old one. So when I was shopping for a new car in 2006 what should I have bought? Should I have bought a diesel that emitted a third more CO2, had loads of NOx, and got less to the gallon?

Please bear in mind that a 50mpg diesel emits more CO2 than a 50mpg petrol.

I'm keen to know – what would you rather I have got? If I were buying now I'd seriously have considered a bluemotion Golf, but they still have higher emissions than a new Prius. So please tell me what I should be driving.

A Prius obviously – just pointing out they're not the "solution" some people seem to suggest (I appreciate that's probably not you – we probably agree more than disagree).

Maverickboy speaks the truth:

The answer also lies with not changing our cars every 3 years (or however long) with them being designed for a 10 year shelf life. It is far less environmentally damaging to keep a 10 year old car running that perhaps does 30mpg than it is to go out and buy a new equivalent that does 45mpg! Mainly because the amount of energy required to make a car in the first place is estimated to equal the equivalent amount of fuel a car will burn in an average 7 years on the road milage!

I've often thought of replacing my 16 year old Isuzu 4wd with something newer – but why? It's still pretty reliable, costs pennies to service & repair and it's FAR kinder to the planet to keep the thing going a few more years than seal the fate of more CO2 emissions buy buying a new or newer car.

People sometimes ask me what car they should get. My answer is "The one you've already got".

I think you will find that a diesel emits less CO2 than a gasoline one. I am also quite sure that the company car tax is higher for diesels to account for this.

molgrips – you mis the point entirely.

You have a car plus a battery. Your improved fuel economy does not cover the poluting cost of the battery and there are many cars with better lifetime polution than a prius bwecause of this. any small supermini for example.

there are no good figures becauswe toyota will not release them. its all about the production and disposal of the battery – that cause more polutiopn than is saved by the hybrid tech.

just stop fooling yourself – the prius is a greenwash.

As a genuine question does anyone have any info on the carbon footprint of Lithium ion batteries, and also info on recycling of them?

Its the recycling thing that intrigues me, as I suspect that (like aluminium and titanium) the engergy to reprocess and OLD cell into a new cell might be much lower than to make one fresh from stuff dug up from the groumd.

just pointing out they're not the "solution" some people seem to suggest

Absolutely. Only thick people think that though. Prius and other eco models are only a very small step. Given the choice I'd rather work from home and not drive anywhere apart from on holiday.

TJ – tell me about the environmental impact of making batteries please. I mean with evidence..? How much worse is a Prius than a normal car in construction? Some figures would be nice.

Here are some studies that support the idea that hybrids are overall eco friendlier than conventional powertrains. However I will accept that they are American studies and therefore compare hybrids with normal petrol rather than diesel cars. However, that is a fair point since hybrids make far more of an impact in the States where smog related restrictions on NOx emissions are very stringent and prevent most diesels being sold.