In article m,
Martin Underwood wrote:

I've always wondered: is it the fact that diesel engines use compression
ignition or the fact that they use different fuel which gives rise their
greater efficiency and their greater torque at lower engine revs?

The lack of pumping losses - due to not having a throttle - was one
reason. But petrol engines are appearing with no throttles too now.

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*Why isn't there mouse-flavoured cat food?

Dave Plowman London SW 12
RIP Acorn