A car running on compressed air

[PMC]

Actually x-ray...

You may be onto something there...  Sprouts, preferably curried could be used to generate an alternative source of high octane biogas, which could then be pumped directly into a combustion chamber and instant propulsion!

[PMC]

Karlos wrote:

That thing delivers more torque at 8000 rpm than most petrol engines do immediately after starting...

Do you mean more torque from low revs than most petrol engines at 8000rpm?  That would make more sense...

Electric motors can produce massive torque very low down in their rev range (why they tend to make excellent powerplants for locomotives for example) but will also rev very highly indeed because there is no reciprocating mass unlike in a petrol engine - unless of course you're talking about a Wankel (fnar) which has very reciprocating mass but low down torque is greatly reduced and usually requires a turbo charger to enhance the torque.

[PMC]

Which leads us back to one other issue that we seem to have overlooked.  

Cars are getting heavier all the time.  Thanks to extra emissions control equipment, rigourous safety standards and the escalating list of optional extras, cars are much heavier today than they were 20 years ago - in some cases by as much as 75%.

A Golf GTI today might have double the power of it's original ancestor, but it's nearly double the weight.  That the extra energy needed to propel the extra mass is not unduly at the expense of fuel economy speaks volumes about modern engine design.

In addition to new hybrid technologies and exotic fuels, we also need to pay attention to how we manufacture our cars. Bucking the trend, a Jaguar XJ saloon is actually lighter than it's predecessor by virtue of switching to aluminium instead of steel for the bodyshell.

There are inherent problems with aluminium; it's much harder to work with than steel, is softer, requires more energy to produce and is as a result costlier, but is a step in the right direction.  Mass produced. composite bodied cars are also some way off, although some companies do use plastic (non load bearing) panels to reduce weight.