Originally Posted by AlterZgo

There is really no evidence that these cars, or any modern cars for that matter, “loosen up” and get faster or more powerful with more miles. Take a look at any Car and Driver long term road test where they test a car new and again at 30K miles. Most perform virtually the same. A small handful perform slightly better and a small handful perform slightly worse. This could be chalked up to different weather conditions and road surface conditions during testing and perhaps a tiny handful of cars do break in and get faster (or slower) over time.

Personally I have never noticed any of my new cars getting faster over time. What I have noticed is the exhaust getting a bit louder and the suspension getting softer and less composed over time as the shocks break in and wear down even with as little as 10k miles.