From what I have learned and read is that you take it easy on the engine and vary the RPMs. City driving is the best.

But I'm wondering if anyone has heard that running the engine hard is the best way to break it in.

Break In Secrets--How To Break In New Motorcycle and Car Engines For More Power (http://www.mototuneusa.com/break_in_secrets.htm)

http://www.mototuneusa.com/BreakInF3Pistons.jpg

These Honda F3 pistons show the difference.

Although these pistons came out of engines which were raced for a full season, they weren't set-up with any special clearances or other preparation.

These engines were never worked on prior to being raced. They were totally stock as built by Honda.

The only difference was the break in method they used...

The one on the right was broken in as per MotoMan's instructions.

The one on the left was broken in exactly according to the owner's manual. The resulting leaky rings have allowed pressure to "blow by" down into the crankcase on acceleration, and oil to "suck-up" into the combustion chamber on deceleration.

Now at first glance it may sound harsh to the engine, but it really isn't when done properly. This is essentially same method that is mentioned in all the manuals for the dozens off R/C engines I've owned. Basically turn on the engine, let it warm up, then give it full bore for a minute, then slowly reduce back to idle for a minute, then repeat. I've broken up all R/C my engines at one point or another for servicing and they all have been in excellent condition without any burnt piston walls. The engines we use in my brothers buggy (VW bug engines) are usually used. We always have to re-ring the pistons or straight up get new pistons eventually and when we open them up to inspect them they always have burnt piston walls. But after we change them and break them in the "rough way" we never have that problem, and the engines do seem to keep their power better (we open up the engine for other reasons however.)I don't know what the manual for my car will say (yes I have an instruction-manual reading fetish) but if it's like every car I've seen before it will probably have a limitation on the RPMs, probably saying to not exceed something like 4500 RPMs for the first 500 miles or so. I'm not too sure I agree with that. My guess is that manufacturers just over-simplify the break in procedure, and 99% of car owners wouldn't be arsed to read the manual anyways.

i dunno good ? tho