> The tax breaks and lower fuel use led to bigger cars. We don't know that. Diesel is far more prevalent with bigger cars because they tend to eat through more

> The tax breaks and lower fuel use led to bigger cars. We don't know that. Diesel is far more prevalent with bigger cars because they tend to eat through more energy over their lifetime, making it more likely to break even on the up-front premium for diesel (not just more joule per kilometre, but typically also far more kilometres per year). But chances are that without diesel, cars in Europe would be just as big today (e.g. they still tend to be smaller that in a certain famously petrol-centric country)