The engines introduced in the late 1990's give much better fuel economy than earlier ones. I read an article in a car magazine a couple years ago about the guy that invented the Oldsmobile Quad 4, who did some other work for GM, was suing Mercedes-Benz for stealing his engine design. Not sure what ever happened with this, but the article said that he was suing to have all cars with the new engines to be recalled and destroyed (?!)... Supposedly MBZ officials met with this guy and basically blew him off.