Quote Originally Posted by MM89 View Post
new cars should be run in hard.
especially with the smooth cylinder surfaces in today's
engines. piston rings need to be heated up so they will
expand and make a good seal; thus no power loss.
True enough, but not running for long periods at constant speed or in the same gear, and building up the use of high revs gradually over 1000 km. Also no hard braking for 1000km.

It's not just the engine that runs in, it's the clutch, gearbox, the diff and the brakes also. Yes run the engine in hard, but vary the speed and go easy on the clutch, brakes and gears. Otherwise the clutch will become grabby and the brakes will vibrate.