Apart from the ignition there is another essential difference between the two types of engine. If you increase the acceleration in the petrol driven engine, more fuel and air are supplied to the engine (quantity regulation). The diesel engine principally, does not alter the amount of air sent to the combustion chamber, it simply provides more or less fuel to the mixture (quality control).

The fuel consumption advantage is the most important argument in favour of the diesel engine. This advantage was made even more obvious with the application of direct fuel-injection. Nowadays however, a number of petrol-driven cars also feature direct injection so that the consumption difference is not as marked as before. The future, as far as economical vehicles are concerned, will most probably be (especially in the partial load range) the diesel engine, despite of the fact that the particle filter somewhat increases the fuel consumption.
Another argument in favour of the diesel engine is the enormous torque available, especially in the lower speed ranges (see diagram on top). It is no longer necessary to shift back to a lower gear to gain sufficient acceleration power at low revs.

The petrol engine has clear advantages too. First of all there is its low weight to power ratio and, above all, the larger usable speed range. (see diagram on top) Truly sporty driving (e.g., with motorcycles) is probably only possible with petrol engines. Also as far as harmful exhaust emission is concerned the petrol engine has the advantage. Basically, the exhaust gas decontamination, (catalytic conversion) which all petrol engines now have, must be applied to the diesel engine. The very fine soot-s will always require special attention, the particle filters are not maintenance free, this of course makes the diesel engine always more expensive. In addition, to exhaust the same amount of carbon dioxide gas, a diesel engine must have a fuel consumption advantage of at least 13% relative to the petrol-driven engine.

The higher the vehicle weight and the more air resistance it produces, the more economical is a diesel engine. Sporty drivers should absolutely favour the petrol engine. A diesel engine will probably never approach the sound of a Formula 1 vehicle at maximum revs.By the way, the fact that there are divided opinions on diesel and petrol engines is due to the fact that the distillation of crude oil produces both diesel and petrol fuel. And the percentages can be shifted only marginally. If too much diesel oil is used, it becomes more expensive and petrol fuel becomes accordingly cheaper.

Imprint