It started out years ago as a 'gentlemen's agreement'. Now, the 155-mph speed limit found on Audi, BMW, Lexus, and Mercedes cars may be lifted after years of being a fact of life. Started as a means to prevent government regulation, this self-regulation is not followed by all manufacturers out side of these four. With more and more manufacturers producing cars that are significantly faster, these four are talking about lifting the limit on their regular production vehicles. The limit removal is being looked into by Audi, BMW, and Lexus. Lexus was not one of the original manufacturers when the limits first were imposed.