There are many options available for a pimped out ride. You can choose how much turbo boost you have, how many ejection seats, different kinds of lights, trims, sound systems, drink dispensers, and windows.
Perhaps the coolest thing is that it allows you to purchase an onboard companion. At first I was going to go with a "Hot Night Elf Girlfriend" who occasionally cast Blessing of Might on me, but I've since decided to go with the "Onboard goblin engineer for emergency repairs." Mainly because I'm a bad driver and have a tendency to smash into other people.