Here is the funny thing about break in periods in cars. Most manufacturers recommed you take it easy with the motor for the first 5000k and other recomendations like that.
Generally the thought from the aftermarket crowd like myself who builds motor we generally do not break motors in at all. Piston rings seat in better in a varying load and throttle conditions.
When you hone cylinder walls it acctually makes them slightly coarse as it cuts ridges in the wall. This helps the rings wear their own groove so the priston ring to wall gap is a tight as possible, (say .014 for the top and .022 for the bottom ring) and the best way to break this whole setup in is with lots of varying conditions on the motor.
Aftermarket breakins are no different from stock for a general street motor. ON a full race setup, we build the ring gaps quite loose as they never see the street, they are built, receive 2-3 heat cycles, then hit the dyno and make 600 or so HP say on our turbo car.
Generally the best way to break in a motor is to beat it right from the beginning. I know this goes against your conventional wisdom but remember what the dealership is telling you is best for warranty, not whats best for horsepower or your driving pleasure. We find the best break in on motors are when they are driven normally right from the start. No full redlines for 1000k but if yoru redline is 7500rpm go upto 6500rpm and use varying loads and amounts of throttle and drive the car car. After 1000k or so change the oil and redline the crap out of it.
My talon I built the motor and it saw 18psi of boost from a large turbocharger on the very ride home from the shop to my house. It sees a lot of flogging and passes at the track and high speed runs on the highway and it never breaks and makes a lot of power and takes a lot of abuse. The 4G63 is not exactly considered the king of reliability but I challange that motor a lot and it never fails, ever.
Here are some other website with the same school of thought.
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Originally Posted by Website link below
For those who still think that running the engine hard during break-in falls into the category of cruel and unusual punishment, there is one more argument for using high power loading for short periods (to avoid excessive heat) during the break-in. The use of low power settings does not expand the piston rings enough, and a film of oil is left on the cylinder walls. The high temperatures in the combustion chamber will oxidize this oil film so that it creates glazing of the cylinder walls. When this happens, the ring break-in process stops, and excessive oil consumption frequently occurs. The bad news is that extensive glazing can only be corrected by removing the cylinders and rehoning the walls. This is expensive, and it is an expense that can be avoided by proper break in procedures.
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http://www.ntnoa.org/enginebreakin.htm
http://www.aircooled.net/gnrlsite/resource/articles/engnbrkn.htm
So the whole point of this is not to worry about the Miles on the car so far as they would have been varying loads from other people which are just helping break in the car. They wont run the car that hard for that long with a salesman in the car. You just need to abvoid lugging the engine hard for long period of time, other then that have at it. Chances are you got a really good break in with all those people driving it at varying loads / conditions...