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Not quite sure what comparing mpg between an automatic family hatchback and a manual supermini proves other than the predictable difference. Anything to make a point I guess.
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Not quite sure what comparing mpg between an automatic family hatchback and a manual supermini proves other than the predictable difference.
I thought that was the point the OP was making - I would have predicated an auto family hatch to have a lot worse mpg than a manual supermini diesel, not as close as this?
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>> Not quite sure what comparing mpg I thought that was the point the OP was making
Ok think I've got it now - sorry, bit slow :-(
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Remember the Prius doing 10 laps at Dunsfold as fast as it could/wanted to and Clarkson going round behind in an M3 and getting 2 mpg better consumption? M3 was a V8 bit I know what capacity - 3.5 or 5 litre?
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I beleve Peugeot are developing a diesel hybrid. Should be the best of both worlds..
www.channel4.com/4car/feature/feature.jsp?id=1202
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Of course you can't glide around in virtual silence, powered only by an electric motor, in a diesel Punto.
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Does anyone know how much it costs to change the batteries on a Prius when they finally go, and roughly how long they last?
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Is it worth trying to quantify how "green" a car is when you look past the MPG figures / co2 figures etc.
How much carbon is emitted building a prius and how much is emitted generating the electricity for electrical cars.
If you care about being green, maybe its better getting a basic, low emitting blueline VAG or 118d BMW. When you consider the co2 impact of hybrid building or the co2 generated from charging up and electric car.
There is no way of knowing the total footprint of the car. I'd be surprised if everything considered that an electric car is greener than a low co2 emitting diesel with DPF and EGR.
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The Pious is a petrol hybrid because it was developed mainly for the US market, who in their worldly wisdom don't 'get' diesel. PSA diesel hybrid coming in a year or so will show what economy can be achieved by a hybrid. In the emantime a lightweight diesel is a far more realistic bet.
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How things have changed, time was a quite sizeable family car would weigh in at a ton, now we have Oily's basic Punto van weighing that...no electric anything..he claims it's for simplicity, i think it's more to do with Yorkshire frugality..;)
Either way the van's fuel economy is excellent.
And until this hybrid battery life, and the costs of replacements which seems a state secret like MP's expenses, is more reasonable and publicised they just won't sell in volume.
By the way Oily, how did the older Punto van compare on similar economy runs...out of interest?
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Diesel/electric plug-in hybrids are the logical conclusion.
Charge batteries overnight - do your first 40-50 miles on batteries, then diesel engine starts up to run generator. That's how the Chevrolet Volt works, except that, like the Toyota Prius, the generator is powered by a petrol engine.
>>Quote:...""[hybrids] just won't sell in volume.""
...Honda Insight was Japan's top selling car in April
Edited by Sofa Spud on 03/06/2009 at 00:20
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I saw two G-Whizes next to each other, plugged into little posts in the street tonight.
How long before eco superactivists with secateurs will be stalking the streets?
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A rival publication which I can't link to here took a Prius II and a 520d on a road trip to Geneva. Not only was the Prius slower, less spacious, less comfortable and less well equipped, but it was actually thirstier too.
Unless you drive in town extensively, the Prius is completely pointless. Most of the examples I see are in lane 3 of the motorway doing about 90 mph, strangely enough.
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>>Quote..""Unless you drive in town extensively, the Prius is completely pointless.""
So really we want a plug-in hybrid with diesel-generator for when the battery runs low, plus a direct mechanical drive that takes over when the car is doing over 50 mph AND the battery is fully recharged.
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I think that it's acknowledged that the Prius is not so economical when it's cruising on a motorway, but if you only do that occasionally and most of your driving is done in situations that take advantage of the regenerative braking, you still don't lose out.
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A rival publication which I can't link to here took a Prius II and a 520d on a road trip to Geneva. Not only was the Prius slower less spacious less comfortable and less well equipped but it was actually thirstier too.
The BMW 5 Series starts at more than twice the cost of the new Prius in the US. So what point is there in comparing them...
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"Not quite sure what comparing mpg between an automatic family hatchback and a manual supermini proves other than the predictable difference. Anything to make a point I guess."
No Stu - You have missed the point. The point of the post was to start a debate about why the new Prius is not Diesel-Electric .
As I wrote "The real point of this post (outside the well meaning snigger) is to ask why they didn`t fit a diesel engine?"
Edited by oilrag on 03/06/2009 at 07:48
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"By the way Oily, how did the older Punto van compare on similar economy runs...out of interest? "
It`s the Mk2b - GB. I expect the Grande Punto van is similar - if not better. Both around 1,000kg I think. Not sure what a Prius 111 weighs in at - (but is there really that much difference between a GP and a Prius in the cab?)
Going off track now - but I would like to see massive tax incentives to get cars down to - say- 750kg - rather than than the Prius route. With effort going into producing larger cars than a city car ( at that weight ) by using modern techniques and materials.
Back to topic
Regarding diesel- electric. I wondered if it was a refinement issue regarding the start-up of the diesel? I don`t see how they are ever going to get a diesel to start at the noise level of a petrol engine. But it seems a shame if it would significantly reduce fuel consumption.
It occurs to me that the petrol engines fuel test figures will have likely been `favoured` by the allowed `California temperature test` re not needing as much fuel enrichment as in our much colder winters.
A 1.8 petrol engine though..... I can`t help thinking a smaller class leading diesel engine would have significantly improved the fuel consumption. Or are there still issues with derv standards in the markets outside Europe for the car?
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>>Regarding diesel- electric. I wondered if it was a refinement issue regarding the start-up of the diesel?
Using some electronic control, there is a better way to start engines if smoothness is your goal.
The wobble you get when starting and stopping a diesel (or any resiliently mounted engine) is the engine passing through the natural frequncies of the mounting system. Normally, these frequencies are a way below the engine's idle speed, and once well above them, the mounting system is an effective vibration isolator.
If, using a variant of Fiat's multi-air technology, you could hold a valve open, decompressing the engine, you could use a starter optimised for speed rather than outright torque, and get the engine spinning at, say, 1500 rpm, all the while getting the glow plugs nice and hot.
With the engine spinning in the speed range where the isolation provided by the engine mounts is effective, the starter would be disengaged, the valves allowed to close, and fuel injection activated. The kinetic energy in the flywheel would allow the engine to start, compression would be more effective at these speeds, and the result would be quite smooth.
I don't know if anyone uses this method - I doubt it - but, the technology is there now to allow it.
Edited by Number_Cruncher on 03/06/2009 at 12:04
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If using a variant of Fiat's multi-air technology you could hold a valve open compressing the engine you could use a starter optimised for speed rather than outright torque and get the engine spinning at say 1500 rpm all the while getting the glow plugs nice and hot.
That's a neat idea, N_C. Like a decompression valve for the 21st century! The more I read about air operated valve trains the better I like them. Camshafts are so last century....
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The Prius has one advantage from the emmisiions point of view, the engine is not running when the car is not moveing. If the Prius is moveing the engine may be running ot may not be but it will have to recharge the battery at some point to make up for the discharge when the car is moveing without the engine running. The only advantage it can ever have is due to bad traffic management.
On the other hand the Prius has to lug round a load of extra weight in the for of bateries, electric motor, generator and goodness knows what other bits and pieces to make the whole lot work. The extra weight means more power used hence more fuel hence more emmisions, not to mention extra wear on breaks, tyres, suspension and of course initial cost plus the cost of battery replacement/refurbishment.
If emmisions are your target forget about plug in rechargeables. They just move the emmisions from the cars exhaust pipe to the smoke stack of Drax B, at least untill we have a widespread nuclear program.
The only thing which does make sense with current technology is to reduce the weight. As oilrag says get the weight of an average car down to 750kg or even less. Get rid of all the sperfluous junk. Who needs electric windows, electric mirrors etc. In this climate who needs aircon provided the car is a reasonably light colour? It would be in the 'nice to have' category a few days a year but far from essential.
Added advantages of lower weight less material and hence less cost and emmissions in manufacture.
Edited by Webmaster on 04/06/2009 at 01:43
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so if the best idea is to get the weight down, then we could all drive something like this :-
www.axonautomotive.com/index.html
or this
evolution.loremo.com/content/view/13/47/lang,en/
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The BMW 5 Series starts at more than twice the cost of the new Prius in the US. So what point is there in comparing them...
Because it was one of the first cars with the Efficient Dynamics system. The article made the point that a diesel engine combined with this technology actually delivers better fuel economy than the (to my mind) ridiculously over complex and heavy hybrid solution.
I suspect if they'd been comparing cars of similar size, the diesel would have been even better. The 5 isn't exactly a lightweight.
The price of the cars involved was irrelevant. It was more a comparison of technology. Plus this Efficient Dynamics type technology will appear on cheaper cars over the next few years.
Edited by DP on 03/06/2009 at 08:38
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It isn't all about economy. The reason Toyota and Honda don't do diesel hybrids is the Nox from the diesel engine.
I think the cost involved in building a diesel hybrid for toyota makes it an unjustified route to follow for mass market affordable cars.
They do already have the "greenest" NOX reduction engine in its class. Something like 0.070g/km of NOX is emitted from the D-Cat engine with DPNR, even hondas closest equivalent engine emits 41% more NOX gases. Then VAG's / fords and pretty much everything else is like 350% more NOX gases.
The D-Cat engine alone is an expensive production item all things considered. I think the research will bunny hop a generation of technology for hybrids.
Edited by OldSkoOL on 03/06/2009 at 10:31
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I saw two G-Whizes next to each other plugged into little posts in the street tonight. How long before eco superactivists with secateurs will be stalking the streets?
Sounds a bit dodgy. Wouldn't it make their hair stand on end?
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Apologies Oilrag, read it again.
Ive always suspected that manufacturers are holding back technology.
I was just reading about the new Lexus RX450 hybrid which now does 45 mpg combined and emissions of 148 g/km. Now thats a 3.5 petrol V6 with 246 bhp in a 4x4. The test said they managed 38 mpg which was presumably on a fairly tight car so it looks realistic. When you consider that your average big petrol 4x4 would barely manage 20 mpg, this is a huge leap and quite exceptional.
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"Apologies Oilrag, read it again."
Accepted Stu. I do have a tendency for eye catching titles....
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