[GeronL]

how fast do they go under caution?

His real mistake is thinking that a guy who slammed him into the wall on purpose wouldn’t do it again

[freeandfreezing]

Sprint cars don't have transmissions or clutches so they have to run at a speed sufficient to keep their engines from stalling. That's one reason you see them periodically hit the throttle during a yellow. A car that can run at 140 mph at 8,000 rpm has gearing around 5.4 to 1. If they really got down to idle they'd be going under 25 mph, but they don't.

In most of the races I have watched speeds under yellow range from about 30 mph to 55 mph (when they rev up).

[freeandfreezing]

His real mistake is thinking that a guy who slammed him into the wall on purpose wouldn’t do it again

His real mistake was losing his temper and getting out of his car. Sprint car drivers are very competitive, and ending up up in the dirt along the wall and losing it are not infrequent events. Had Mr. Ward had the ability to drive down into Stewart he might well have to force him back, but he probably couldn't because of the limited traction where he was. Watch some sprint car racing, you'll see some pretty intense driving.

It is a terribly sad situation for Mr. Ward's family, friends, and everyone who loves the sport - including Mr. Stewart.