How many races are there available in Wellspring?

I completed all three events Slim has to offer and was wondering if there are any other races I can do to earn upgrades for my car.

I also did the sponsor race to get an upgraded buggy, but are there any other races in Wellspring?

Not including the races from Slim, You can race Starky, who is apparently the top racer in town. He can be found standing around near Slim. Racing him and winning will give you an upgrade for your car.

Starky became available to me to race after completing all the Slim races. I completed them all in first place, but do not know if this is a prerequisite to getting access to the Starky race. I didn't actually check if he was available at some point sooner.

Updated*

Including all the races in the three events, there are no more races in Wellspring available. In total, 16 races are available in Wellspring. You can do 11 more races and if you win all of them, you will earn the Rage Cup Achievement/Trophy.

I believe those are the only races in Wellspring since there is another city that has the fourth racing series.

you may get racing certs by destroying buggies in the wasteland. ;)

edit: oh yeah, there's Starky too.