The OP was thinking of getting a diesel but was worried about maintenance costs and you suggest an M3 that does about 20miles to the gallon and with roadtax just under 2grand?
with 8grand you'd pick up a decent 2008 1.9tdi golf with low road tax
And you would get the petrol variant cheaper again.. point is this person does not do enough miles to make a desiel a more economic choice... Do you get that, very short trips are not good for turbos, maintenance in general is more expensive for desiel engines. The savings on fuel only kick in once the engine is warm. The wear on a desiel if only doing short trips will cost you (turbos, injectors and partical filters)... But hey don't listen to me listen to people that think the only cost in running a car is tax. Btw e46 m3 is 1809 tax