Some people believe in soft break-in, and some people prefer to drive it like you stole it. Both methods have worked well from what I have seen. The important part about the second method is that the car has to be warmed up well before you start revving it up to redline. People who go by that method say it seals up the piston rings better.

In reality, I don't think break-in methods have a lot of impact on the engines as it is not like the engine has never run in its life before. It's all tested from the factory to insure that it runs properly from what I know. I personally think the hard driving method works better, though.

What I worry about the new cars with many miles is that those cars might not have been warmed up to operating temperature at all before being driven hard, which I believe would happen at almost every test drive.