Don't take the family, or luggage. Lose as much weight as possible. Remove stereo/speakers/passenger seat. Don't turn on the AC but keep the window's rolled up. Get an oil change, check your filters. Air up your tires to maximum recommended on the tire not the label on your door. for entertainment bring a ipod Nano (the light weight one). Good luck.

Ok you know I'm just josh'n. If its near time to get your oil changed do it. Check your air filters. Wash and wax your car and air up your tires. Enjoy your trip.