192HP is the factory rating at the crank for the Coupe (and SLK230), some put out more, some less . The dyno above is a chassis dyno so you have driveline losses from the drivetrain. It would be cost prohibitive to pull the engine out, intake, exhaust and set it up on an engine dyno. Some believe these numbers to be about a 15% loss for a manual trans car. So in theory a car that is 192HP at the crank would be 163 Rear Wheel Horsepower (RWHP) and I've seen as low as 159 rwhp to 176 rwhp from different Coupes on chassis dynos. So using the 15% drive train loss (more for an automatic), the 197 rwhp is really about 227 hp and the same goes for torque, the really more impressive improvement.

Not bad when you consider a $40,000+ BMW 330Ci coupe is less HP than that and way less torque.