When does an S4 engine run in?

I would say the engine will give its best performance and economy after about 10k, that's pretty normal these days,

But that's just loosening up not running in,

Modern engines need less than 1000 miles to be run in, although are now made to such tight tolerances that they need very little,


Brand new cars are driven hard from stone cold straight off the line as they are put through brake tests and some are pulled off line for about 10 miles of test track time too,