hey vracer CLA does have overboost just not advertised. Same as BMW's 'button'. Mate the CLA's pedal with its floorboard and you'll see an extra 13hp and 15 lb-ft in breif bursts. 2014 Mercedes-Benz CLA 250 Sport First Drive - AutoblogNashville brings up a good point. While the generally accepted loss is 15%, it varies by lubricant, engineering, fwd vs. rwd, auto vs. manual (don't forget this car does not have an automatic, it has a 'dual clutch', and "could" be as efficient as a manual), and finally the dyno itself.
Even though most dyno operators try to adjust for standard conditions, it is rare to find two dynos that produce the same numbers, even machines from the same manufacturers. Take all these numbers with two grains of salt. Tuner A's dyno will show 200 whp while Tuner B will have 215. Is B better? The answer is only, maybe.
its mechanical drag. When you measure power at the crank like most published stats are you bypass the mechanical drag that comes from gearbox and driveline components, the CLA difference between dyno and crank measurements is ~12% pretty average IMOa drop of 27 horsepower is not terrible but it is significant. I bet you that Mercedes published the best possible scenario for the CLA. But when you test it in the real world there is variation.
Might be time for car makers to start giving us numbers at the crank and to the wheels. I would like to know both, so would many others.Dynos will always read lower than what manufactures rate them at. Wheel Horse Power is different than Crank hp which is how all manufactures typically rate their engines using engine dynos. Ive heard Renntech is in the works of a plug and play tuner which should be released in the next 6-8 weeks.