Diesel vs Petrol

[jopsuk]

That's sort of, with the addition of having batteries for emission-free city driving and regen braking, what hybrid cars do.

 

[LE Greys]

Aviation gasoline (petrol) used in aircraft piston engines was OK to use in cars of old. But do not use it in a modern car with a catalytic convertor. It has a very high lead content, and that will kill the cat. Your car will fail it's next MOT, and you will have to find several hundred pounds for a new cat!

This was early 60s (certainly before 1964). Not sure what the make or model was, I'd have to ask my mother.
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The GTMU certainly sounded familiar, I wish I'd known they existed before now so that I could have gone and seen them.

 

[ChrisCooper]

Why don't cars do the same as many trains and have diesel engines supply power for electric traction motors. As full torque is available with these electric motors there wouldn't be any need to change gear.

The thing is it's heavier, less efficient, more expensive and more complicated (and therefore more likely to do wrong) than mechanical transmission. It's only now with lighter weight motors and better batteries that diesel or petrol electric hybrids have become viable and can beat straight mechanical transmission on efficiency, but they are still heavier, more expensive and more complicated. Diesel Electric only became standard on trains because it can take much higher power and torque than mechanical. Then again for lighter and less powerful rail vehicles, mechanical has always had the upper hand, such as on the first generation DMUs and now the 172s.

Some early buses were Petrol Electric, but it didn't last long at all.

I think most hybrid cars have gears anyway, even automatics. A lot of hybrid buses do too, although some have the motor directly driving the wheels. Thing is, some hybrids the engine is still directly driving the wheels through a gearbox, then the motor is connected via a clutch so it can either power with the engine and boost power, be driven by the wheels for regenerative braking, or be driven by the engine for battery charging.

 

[Malderon]

I think in car terms the closest you get to Diesel/Petrol Electric is the new Chevvy Volt / Vauxhall Ampera.

As I understand it once the batteries run out of charge at low speed it will essentially be running as a Petrol-Electric, the ICE will engage to act as a generator.

However at high speed the petrol engine will also have to provide some mechanical power.

At least the BMWs with EfficientDynamics and competing systems get some of the benefits of a car with electric tractionl. Because of their stop start system they use alot of battery so they have regenerative breaking to recover and keep it charged.