cartmen34

At an F1 car's maximum braking force, a driver is placed under 4+ G's of negative G-force loading. Brian Herta, after his F1 test, was quoted as saying that when the car shifted gears "it felt like someone punching him in the back", or something to that effect. Just imagine doing 4 negative G's and being punched in the back, depending on the track, anywhere from 6 to 13 times a lap, for 60+ laps. exhausting? Me thinks so.

And lest we not forget that CART had to cancel an event at Texas motorspeedway in 2001 because the drivers were getting dizzy because of the G force effect. Over the planned 600 mile event, the drivers would have been subjected to 4.74+ G's every 5 seconds, more than 800 times. Unconsciousness ensues.
Edit:
I got these facts from this article: http://www.howstuffworks.com/question633.htm

Nascrap cars wouldn't even stick to the track long enough to generate these kinds of forces.

Edit, part Duex:
Upon further investigation, I see that several guys already mentioned this...Serpent, Spyder_Venom, Glober also voiced the same opinions

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