Go with the 24'. I did 8.5' for my X, $50 less at the time. It works fine, but only for one car parked the same way all the time. I'll get a 24' when we get the 3. That allows us to mount it on the wall to the right of the car and reach across the back of the car to the charge port on the left, or charge if we pull in backward, or possibly charge other cars in the garage. The 24' would have been tough to coil up where I have the 8.5' connector, but would have been able to reach any car in the garage. Just tie up the excess if it's too much for now.