Why? I go for trips that often exceed 10 days, it's cheaper to pay for car service then paying to park for 10+ days. I don't have to worry about my car getting broken into/damaged, and they take you right to the terminal, none of the shuttle bus garbage to deal with. You can sleep to/from and it's just one less thing to worry about.
Well, I do, too - but I manage to just take a *taxi* to the airport. I don't need a "car service" with a chauffeured limo.