I've got a new to me 500E. Nice car but why does it shift at 4000rpm in first? And that's if I can get it to start in 1st, usually it won't. Isn't it supposed to shift at 6000rmps? Other symptoms are that it is flakey on the downshifts. It often won't downshift at all, and when it does it will only drop 1 gear. If I am cruising at 55mph and want to pass, shouldn't it shift from 4th to 3rd to 2nd? Also I just took my first day trip in the car and got only 16mpg overall. If I were driving about 80-90mph most of the time with A/C, would this be acceptable?

Thanks,
Eric