Not sure if the tank is bigger. But i run my car down to zero miles before filling it right up again. Sometimes i can run on zero for about 10 miles! At least i know there is a reserve tank. I always have to fill up at Shell, so if its on 1 miles, i risk it and travel to my local shell station!
The last fill was £43, the one before that was £39. Definately a smaller tank than the old mini one, i could fill that with nearly £50 and it would last 5 days! At least my R56 one is cheaper to fill up, and i can run it for two weeks no problem.