Does anyone here watch any motorsports races? If so, what was the most horrible motorsports crash you've ever seen?

For me, the most horrible motorsports crash I've ever seen was this one in the following video:

YouTube - Michael McDowell Nascar Crash 4-4-08

April 4, 2008. Michael McDowell, a NASCAR Nextel Cup rookie, was performing a qualifying attempt for the 2008 Samsung 500 at Texas Motor Speedway, when his car suddenly lost control and smashed into the wall, causing the car to barrel-roll several times while shedding debris everywhere AND with fire coming out of the engine compartment! But the most shocking thing of all is that he walked away completely unscathed!

What was the worst motorsports crash you've ever seen?