Several of the sponsors rent larger cars, just check out their websites from the sponsors list.

However, as Kim said, a Corolla will fit 5 people. Something larger than that is going to cost a LOT more than a Corolla. What's the configuration of your group? If there are 4 adults, you might want to get two vehicles, as it will be about the same cost as 1 larger vehicle, and small cars are much easier to park. Going out to dinner, you can still all squeeze into one vehicle if you want, but gives you more options during the day. Now if it's two adults and 3 kids, two vehicles won't work, but would be easier to get 3 kids in the back of one car to begin with.