...rule changes? This goes back to the 1960s. Chevy couldn't compete with the Chrysler Hemi so they whined until NASCAR effectively banned it. Then Chevorlet whined about Ford's proposed 427 and NASCAR banned it before it even ran. Then when Bill Elliot and other Fords were faster than Chevrolets, NASCAR mandated restrictor plates in the guise of safety. Now Chevrolet is whining about Toyota power and once again NASCAR changed the rules so the Chevy's can compete.
Why does NASCAR not tell the Chevy people to make a better engine instead? France family ownership of Chevy dealers perhaps?
See this link for the latest rule change:

http://www.nascar.com/2008/news/headlines/bg/07/23/engine.rule.amendment/index.html