I am thinking of buying a 2nd hand Toyota Prius but almost all the driving I do is on the motoway - usually between London and Wales. I have been driving an old SAAB 900 automatic, which I need to get rid of but the car is fantastic on the motorway, though very thirsty. I really want to make sure that I but a good automatic car which is good on the mpg but which also has the kind of performance that I am used to which makes this commute viable. I am particularly concerned about acceleration and speed. I usually do a steady 75-80 on the motorway. And acceleration is easy. Is a Prius OK from this point of view and will it use less or more petrol on a run? I'm confused.