The A590 can do manual which you can set the shutter speed. He might be okay as long as it's day time. There's no way he can shoot at night races though and he'll have to be pretty close.
I want to buy my 21-yr-old son an inexpensive camera. He is into cars and racing. The races he shoots are at a local raceway park where anyone can participate. These cars usually don't get much over 100mph. He needs a point and shoot with a good stop-action feature. I know I'm not going to get top quality at the price I want to pay (around $150) but I'd still like some suggestions or any helpful advice.