I agree with Phil and Huh - d2xdt2 But that's acceleration - I don't think of Audis. I think of Corvettes, Cobras and Vipers. When I think of Audis, I think of handling and cornering. I know, how about angular acceleration: d^2(theta)/dt^2 or d2thetadt2 - Doesn't have that ring to it, does it? Bob Cummings 87 Coupe GT