We test drove both yesterday. 3.0 w/o sport and a 4.8 loaded. The 3.0 was very smooth, quiet, and well mannered. The 4.8 had tons of torque and hp and was significantly faster and had a louder exhaust note. We have an M5 and our 325 had the sport package so we are somewhat use to the firm ride. We may need to tow a jet ski once in awhile so the 4.8 would probably be our choice. The mpg difference doesn't bother us as we don't put too many miles on our cars.