FWIW, the non-M Z4 coupes are slightly more practical because the battery's not in the trunk taking up a huge chunk of storage space. Not that these are practical cars to start with. --Andre Actually, they're about as practical as you can get for a 2-seater. The si coupe has 10.1 cu ft of trunk space. Compare this to a Civic sedan, which has 10.4. Also, people on bmw forums report getting over 30mpg for highway cruising.