Sonic in a car.

[Chaosenemy]

Sorry, what?

[Atome]

He would win all the race without one.

[NBlastMax]

It's for fair competition.

[ezodagrom]

Pretty much what Atome and NBlastMax said:

He drives the Speed Star - a car built by his friend Tails - it helps to make a fair race as no one can beat Sonic on foot.
http://img215.imageshack.us/img215/2774/sonicsegaallstarsracingh.jpg

[scy1192]

Sonic R seemed like a pretty fair race, I'm not sure if I buy that explanation. Sonic being in a car isn't unprecedented, though.

[sayed_stafa]

sonic hurt his ankle and doesn't want to walk around with a limp

[Chaosenemy]

sonic hurt his ankle and doesn't want to walk around with a limp

Poor fella.

[User_Name_Here]

Sonic R seemed like a pretty fair race, I'm not sure if I buy that explanation. Sonic being in a car isn't unprecedented, though.

Sonic R was made back when Sonic was only slightly faster than Tails and Knuckles. Modern Sonic with his speed boost is much faster.

Though now that I think about it, didn't Sonic and Mario at the Olympics feature a foot race?

[Count_D]

At first, they tried to have a mixture of different gameplay styles in one race, but that didn't work too well, so they made a straight-up racer and since an on-foot racer controlling like a car is weird (and no, Sonic DOESN'T control like a car in modern games), they decided to just give him a car.

[Mavrickindigo]

Sonic R was made back when Sonic was only slightly faster than Tails and Knuckles. Modern Sonic with his speed boost is much faster.

Though now that I think about it, didn't Sonic and Mario at the Olympics feature a foot race?

Yes, but Mario is faster than Sonic in most of his games. It's just not a thing they like to flaunt around

[GAmbrose]

Errrrm, it's a game...

That's why.