WatchProSite|Market|Digest

Automotive

I think the model number followed the engine and the engines were based on the country/market.

 

ROW=M88=M635csi
US=S38=M6
The US engine was down a bit on top end power and compression but made better low end torque. The M88 was wonderful but it didn't make its full potential in the US with relatively low octane gas. It would ping on 91, needed 93/94 octane at least in my car.

  login to reply