i've been pretty happy with reserve C, drive F for most rentals. it's usually a taurus, a camry, or a small SUV (escape, outlander, etc). you'll get the occasional D (two door mustang or grand prix), and the occasional YC, tho i've had no trouble turning those into F's. the only gotcha is seattle -- reserve F there, and hope for the official flyertalk YF impala, because that's about the best you'll do on an F res there..