Error, this does not compute.. Arriving in the afternoon after leaving the same morning? You are aware its over 2000kms, and therefore takes more than 20 hours driving?

I wouldn't even think about it, a couple of friends did that drive a week ago to pick up a new car... 24hrs of driving with minimal stops for fuel and food, and they wouldn't have been driving slow. Even with two people to split the driving duties it's just plain brutal. Buy a plane ticket.. your body will thank you for it.

If you do decide you are crazy enough to do it, why can you not just do a key drop return on the Sunday morning? Park the car in the rental carpark, fill in the paperwork and just drop the keys into the return slot at the unmanned counter at the airport. Its exactly what I did for a similar situation earlier this week.