I bought the '03 540i with M Sport Package Steptronic Transmission, Nav black on black and I couldn't imagine driving the V6. This car has head jarring torque, it scares all those in the passengers seat, and the 18 inch wheels make the 290 horses stick like glue. I heard the 525/530 handles a little better because they're lighter and weight distribution is closer to 50/50, but I'd rather have the power, knowing this is one of the faster cars on the road, you can't help but use the autostick at red lights. Other cars must respect this car on the road, and for all those who complain about the cupholder, you can buy one that goes in the slider drawer and pops up for $89 online.
Power and the 18 inch rims. The opened exhaust with the M package and all the M badging is a very nice touch closest thing to the M5. Sounds and drives great.
I just got this a month ago so I am pushing it, and my gas mileage is only around 16 mpg, on the open road it does much better around 24, I'll alter my driving to strive for 20 overall. But it's just too much fun to care about the MPGs.