Get a 5.0! I had no big problems in mine... besides that one time the altenator went out as I was passing compton....
And gas hog? I was able to get a best of 21 point something miles per gallon, while I've only been able to get a tad over 23mpg with my m3. And both are with a good amount of highway cruising and good ol' throttle stompin'.
Don't go get yourself a money pit by spending 6g's on a bimmer. Soooo many little electrical problems and little things falling apart. And not enough speed.
5.0 man!!!