automatic gear in diesels

[FLORIN70IL]

There is sometime I'm trying to find an explanation for the facts that most of the diesel cars are not available with automatic gear Maybe I'm wrong but a diesel engine seems to me more suitable for an automatic gearbox than a gas unit due to more torque at lower RPM.Is have to be a problem but I cannot figure what could be.Second,despite
torque/RPM ratio of the diesel,two identical cars one with diesel engine and the other with gas engine with the same power and weight,almost in any case,the gas engined car is quicker and faster than diesel car. How is come?

[DasModell]

power/torque curves ..

[henk4]

Originally posted by FLORIN70IL
There is sometime I'm trying to find an explanation for the facts that most of the diesel cars are not available with automatic gear Maybe I'm wrong but a diesel engine seems to me more suitable for an automatic gearbox than a gas unit due to more torque at lower RPM.Is have to be a problem but I cannot figure what could be.Second,despite
torque/RPM ratio of the diesel,two identical cars one with diesel engine and the other with gas engine with the same power and weight,almost in any case,the gas engined car is quicker and faster than diesel car. How is come?

The gain from an automatic is a reduction in gear shifting manipulations. Diesels are normally so torquey that hardly have to switch. I can drive away in second, shift to third doing 15 kph and then shift to 5th when doing 60. Alternatively I can move the car up to third gear without even having to touch the throttle, in other words on the tick-over. So the automatic does not bring so much additional confort. although most of the larger audi's bmw's and benz diesels are fitted with an auto box.
You are probably right about the redlight sprint, it may also have to do with the flywheel in the diesel, which you will notice immediately when shifting up. Also because of higher revving gas car you can stay longer in first gear, so you may win a few meters there. Where the diesel wins is when you accelarate while already in motion.