I think the crux of the matter is we have to assume that drivers will never be able to get the best out of their cars due to lack of ability for what ever reasons then the car makers should design in this issue so that the punter has no choice but to drive in that manner.

I can see things changing so that there will only be 1 engine worldwide - super charged & turbo charged (petrol or diesel), this vast scale production will really cut down on the countless factories creating slightly different engines which lets be frank are all now starting to output very very similar max bhp/ltr.

The other benefit from this is that at 17 you have up to xbhp then 21 xbhp 25 xbhp this will drastically reduce insurance costs as they will not be permitted to drive high power cars and when they "come of age" they dont need to buy a new car its just remapped by the garage to the next desired bhp.

Now you're just being silly?

If the fuel tank was halved from 63ltrs - which is a lot of weight its like 4 packs of 8 2lts bottles of coke. that would make a big weight saving.

Downside more fuel stops - is that really a downside?

Or how about this - at motorway speed the engine shuts down cylinders so that it only needs xbhp to maintain the speed.

IIRC only 50bhp is required to maintain 75-80mph

Ok so on the solar panals according to your numbers the power that can be generated is 100-150W but the air con requires 1000-1500W. This to me means only one thing they need to make the air con run on less power - make it more efficient.

If using solar power & the necessary R&D to create a 150W car air con work is too high then using breake regeneration power is the clear answer, why waste all this kinetic force - have it charge up a 2nd or larger battery to run the air con exclusively.

With the education of drivers - you always going to have vast differences between drivers as at the end of the day noone is the same. You could argue that anyone over 15 stone shouldnt get in the car or if your not carrying passengers take out the back seats.

Just thought of another simple way - tyres, clearly first everyone should ensure they are inflated correctly but after that tyre makers should be making them with less rolling resistance while still maintaining braking & cornering grip levels.

You must have posted this whilst I was typing something else:

1. A 1000% improvement in efficiency for air con will be impossible. I'm sure it could be improved by a few % by using larger heat exchangers etc. but there'll always be a certain energy requirement of not less than the total energy removed from the air in the process of cooling it. The law of conservation of energy strikes again!

2. Brake regeneration ONLY WORKS WHEN YOU'RE SLOWING DOWN. And what about the extra weight your second battery adds? And the alternators used for regenerative braking, while we're at it. All these things will have well sub-prime efficiencies, in which case, the fewer systems and components the better!

3. Why is educating drivers such a daft idea? It's one of the few New Labour Nanny-State ideas I actually agree with.

4. You can't maintain levels of grip AND reduce rolling resistance. The two go hand-in-hand. And having driven a car on Michelin Energies, I can say that fitting them on every car would help reduce emissions, but it'd be carnage on the roads every time it rained!

Or how about this - at motorway speed the engine shuts down cylinders so that it only needs xbhp to maintain the speed.

This has been done on big engines with 8 or more cylinders. At part-throttle cruising, half the cylinders can be dropped out. Can't remember who.

Problem is, on a engine with fewer cylinders, the engine runs badly due to the imbalance once you remove cylinders from the firing cycle, and as most cars have 4 or fewer cylinders (as a 4-cyl or less is cheaper and easier), this idea becomes impractical for the bulk of cars.

If the fuel tank was halved from 63ltrs - which is a lot of weight its like 4 packs of 8 2lts bottles of coke. that would make a big weight saving.

Downside more fuel stops - is that really a downside?

Or how about this - at motorway speed the engine shuts down cylinders so that it only needs xbhp to maintain the speed.

IIRC only 50bhp is required to maintain 75-80mph

1. Going to those lengths shaving 30kg from a car weighing in excess of 1000kg is in the same league as your "take the back seats out when you don't have passengers" comment IMO.

2. Shutting down cylinders only really works if you have more than 6. Then you can shut down 3 and keep 3 running. You could run a 4-cylinder car on 2, I suppose, but it'd be well rough. You can't do things like run a 4-cylinder on 3 or a 6-cylinder on 4, as they timings will be all over the place so you'd need multiple cams and crankshafts(!). And anyway, running your ordinary engine on a ligh amount of throttle does exactly the same thing, so why bother...?

If that is the case (which I believe it is) then shouldnt all automatics be constantly variable to ensure engine revs are maintained at that level.

The problem is building a CVT that will handle the torque load.

The Audi CVTs have artificially limited peak torque compared to a manual to avoid breaking the transmission, and even so they don't have the best reputation. Ford Fiesta and Nissan Micra CVTs are renowned for failing at relatively low miles despite the fact that they are light and have low-torque engines.

The reason most auto big cars have a torque converter/epicyclic gearbox, despite the poor efficiency, is that they can handle the load.

Ok how about this - the old fashioned overdrive?

A super long 5th/6th/7th gear where at 70mph even petrol engines are reving at about 2000rpm rather than 3-4000rpm?

WIth the air con it might have to be a totally new technology which can run on 100-150W. If Air con uses energy like a kettle does its highly energy consuming, however having said that in real terms it doesnt add that much to the fuel usage few mpg.

I also have read that the science over window open vs air con on is that at speeds up to 40mph window open is the most efficient yet over that speed the drag caused by the open window negates the mpg used by the air con being on. Also when car is stationary even with windows open it does nothing to cool you down in fact with all the other car engines running your probably going to get hotter.

The other option is to use a dry cell battery for the air con much lighter than a wet battery.

This has been done on big engines with 8 or more cylinders. At part-throttle cruising, half the cylinders can be dropped out. Can't remember who.

Was it Cadillac with a 12cyl engine? Trouble is, if I'd paid for 12 cyl, I'd want to be using them all, all the time!

Chris

Was it Cadillac with a 12cyl engine? Trouble is, if I'd paid for 12 cyl, I'd want to be using them all, all the time!

Chris

I think it was, yes.

1. Going to those lengths shaving 30kg from a car weighing in excess of 1000kg is in the same league as your "take the back seats out when you don't have passengers" comment IMO.

2. Shutting down cylinders only really works if you have more than 6. Then you can shut down 3 and keep 3 running. You could run a 4-cylinder car on 2, I suppose, but it'd be well rough. You can't do things like run a 4-cylinder on 3 or a 6-cylinder on 4, as they timings will be all over the place so you'd need multiple cams and crankshafts(!). And anyway, running your ordinary engine on a ligh amount of throttle does exactly the same thing, so why bother...?

Ok so we save 30kg from the fuel & then lets assume 30kg from the back seats your looking at a 6% reduction in rolling weight - You now will need 6% less power to accelerate as you did or to maintain the speed.

Using plastic wings and thinner glass will also save some more weight.

WIth the air con it might have to be a totally new technology which can run on 100-150W. If Air con uses energy like a kettle does its highly energy consuming, however having said that in real terms it doesnt add that much to the fuel usage few mpg.

The other option is to use a dry cell battery for the air con much lighter than a wet battery.

You're off the map with this, I'm afraid. Let's say the fans in your car do an air change every five minutes in your car. That's something like 2 cubic metres of air every minute. To cool 2 cubic metres of air from, say, 28 Celsius to 18 will take at the BAREST MINIMUM 435W. That assumes prime (i.e. 100%) efficiency from the compressor, condensor and heat exchanger, and no heat transfer across the walls of the coolant circuit. This is impossible, and in reality the overall system efficiency is more like 30-40%. Hence the need for a compressor rated at 1500W. And the thought of running that off its own battery is faintly ridiculous for reasons related to my regenerative braking post...

Ok so we save 30kg from the fuel & then lets assume 30kg from the back seats your looking at a 6% reduction in rolling weight - You now will need 6% less power to accelerate as you did or to maintain the speed.

Using plastic wings and thinner glass will also save some more weight.

Less power to accelerate, yes. Maintain speed, no. That's got far more to do with air resistance. A heavier car will have more momentum, and will therefore tend to maintain speed BETTER than a lighter one. Swings and roundabouts.

Ok then heres an idea on hot days you put up blinds in your car on the windows (maybe electric to may it easier) then when you get inside your car it will be much cooler so you dont use the air con so much straight from the off + the added security benefit of privacy.

Ok then heres an idea on hot days you put up blinds in your car on the windows (maybe electric to may it easier) then when you get inside your car it will be much cooler so you dont use the air con so much straight from the off + the added security benefit of privacy.

Not sure electric blinds on all the windows would be legal - I certainly wouldn't feel safe: what if they went wrong?! Anyway, the pre-drive cooling's already been covered.

And I'm finished here, too. Enjoy the debate!

Isn't this mainly due to the use of torque converters? If you had an automatically operated plate clutch and gearbox you'd get a more efficient automatic.

Rob.

So kinda like a Smart then?

So kinda like a Smart then?

Now you come to mention it...

Rob.

And I'm finished here, too. Enjoy the debate!

So anyone else got some MPG saving revolutionary thoughts?

Ive come up with a few

So kinda like a Smart then?

And the DSG.

So anyone else got some MPG saving revolutionary thoughts?

Ive come up with a few

hardly, the car needs to be re-invented to be more economical. You've tried to skim a little off the things we currently have. Why for instance does a typical car weigh far in excess of 1 tonne?

And, wtf has this got to do with the golf gt tdi?

A golf GT TDI weighs over 1 tonne?

Do I get a prize for the tenuous link :P