You can drive until you run out of gas. I bought a new DB9 from a dealer in Houston and drove it back to New Orleans - roughly 350 miles - and there were no issues at all. The only thing you need to be careful about is not staying the same speed for long periods of time. The worst thing you can do is get on the interstate and set the cruise control and ride the entire way at the same speed / in one gear. All that means is you need to take every opportunity you can to punch it a little here and there. I was worried about the same thing you are, but there's no break-in period for the engine or anything...my dealer's recommendation was to drive the car like it's meant to be driven and not to baby it. I had no issues with complying.