Regarding the poster who doubted the real-world performance of Diesel engines: he should take a look at the torque curve of a modern turbodiesel. The torque levels available from even a modestly-rated modern Diesel make highly-tuned spark-ignition engines look a bit sick. And while the peak revs are not as high (helping to reduce frictional losses, by the by) appropriate gearing can ensure that you get plenty of thrust at the contact patches - which means that midrange acceleration is excellent.
Automobile drivers are only using a small fraction of their engine's potential power output most of the time on the road, but if you want to accelerate hard at any given speed and in any given gear, you are likely to be using 100% of the available torque. So torque characteristics (and appropriate gearing) are more significant than peak power.
A little smoke (no smoke, in the case of the latest catalysed engines) is a very small price for the massively higher efficiency (both theoretical and actual) of the Diesel. If it's getting the same on-road performance but using 20 or 30% less fuel, it must be doing something right.
One last thought:
Heavy trucks always use turbodiesels: in hilly conditions they will be using 100% of the available torque and, quite often, 100% of the available power (the figures are typically 2,000Nm @ 1,200rpm and 420hp @ 2,000rpm for a 12-litre engine). And yet a decent driver would expect to get around 7 to 9mpg from a truck weighing 40 tonnes all-up; compare that with the 30-40mpg you would expect from a 1.5-tonne automobile.
A remarkable difference in efficiency, wouldn't you say?
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Regarding the poster who doubted the real-world performance of Diesel engines: he should take a look at the torque curve of a modern turbodiesel. The torque levels available from even a modestly-rated modern Diesel make highly-tuned spark-ignition engines look a bit sick. And while the peak revs are not as high (helping to reduce frictional losses, by the by) appropriate gearing can ensure that you get plenty of thrust at the contact patches - which means that midrange acceleration is excellent. Automobile drivers are only using a small fraction of their engine's potential power output most of the time on the road, but if you want to accelerate hard at any given speed and in any given gear, you are likely to be using 100% of the available torque. So torque characteristics (and appropriate gearing) are more significant than peak power. A little smoke (no smoke, in the case of the latest catalysed engines) is a very small price for the massively higher efficiency (both theoretical and actual) of the Diesel. If it's getting the same on-road performance but using 20 or 30% less fuel, it must be doing something right. One last thought: Heavy trucks always use turbodiesels: in hilly conditions they will be using 100% of the available torque and, quite often, 100% of the available power (the figures are typically 2,000Nm @ 1,200rpm and 420hp @ 2,000rpm for a 12-litre engine). And yet a decent driver would expect to get around 7 to 9mpg from a truck weighing 40 tonnes all-up; compare that with the 30-40mpg you would expect from a 1.5-tonne automobile. A remarkable difference in efficiency, wouldn't you say?