On Saturday, we are starting a 39 hour road trip. I have a small Cadillac SUV with a car top carrier. We will most likely have around 8 suitcases when all is said and done. I'm pretty sure this is going to be bad on my gas mileage- is there any way to calculate HOW bad?
Well, the car top carrier will add mileage, Is it a top box or an open roof rack? If it's open, pack it so it's as streamlined as you can make it, with no flapping material or flying strings. Spread the weight in the car equally, to make for better performance, and drive about 10 miles an hour slower than normal. That will help minimise the mileage loss. I'm afraid I don't know how you'd calculate the loss with any accuracy.
