Turbo Kate wrote:
“Even thought the initial cost is always higher than a petrol model, and the fuel is more expensive, they still save money in the long run.”
As for the price of diesel I think UK is an exception. In other European countries diesel is cheaper than petrol, as much as 15% in France, for example. In addition, diesel is packed with more energy source (hydrocarbon) per volume than petrol, again as much as 15% more. Even though the tax incentives on the vehicles are almost gone as Turbo Kate mentioned, still the above two points are the main reasons why economy-minded Europeans buy diesel automobiles. It is not because diesel vehicles are better performers. (Engine is heavier and the maximum power output per displacement is less.) It is not because its exhaust gas is cleaner. (Actually it is more difficult to clean the diesel emission.)
Because of the demand from the economy-minded consumers European manufacturers spent tremendous amount of money in diesel engine R&D. Now they have to amortize this investment by selling more diesel automobiles in NA, where diesel fuel is not any cheaper than petrol, and there are no tax incentives for diesel automobiles. So European manufacturers had to take a different strategy in selling diesel automobiles to diesel-allergic (got burned by GM passenger car diesel engines) NA consumers. So now they say “Diesel has more torque” (Yes, but the engine gets out of breath by the time it reaches 4500rpm, from where the real driving fun starts), “Diesel is more economical” (Yes, as long as fuels are sold by the volume and not by the weight or by their energy content) and “Diesel emits less CO2 per mile” (Yes, by the rate of efficiency difference. But it is not really cleaner).