Let say that a person is interested in buying a new car aka used but not USED.

Would you be worried about what the former owner did? My main issue is that I want to know for sure if he/she broke in the motor and transmission properly? What would happen if the fella just brought a brand new car and drove it around normally, is that considered somewhat proper breaking in procedure? What would be the consquences of not properly breaking in hte motor/tranny and when would it show up?

I would have to agree with Darrel here, in that you have to assume that any used car did NOT get a proper break-in. With that out of the way, your interest should now be in getting a feel for the person who has the car for sale, assuming they were the original owners.

Everybody will likely tell you that they were really good to the car since they are trying to sell it to you. That'* where your ability to get a feel for character using visual cues and by simply chatting with the person comes in. Additionally, pay attention to any clues that the car gives you.

A thorough check, inside and out and underneath and under the hood will tell you a lot about how the car was cared for. A quick scrub-up cannot hide a lifetime of abuse.

Then, if you need the expertise of others and there'* not a handy BC member near you, pay a certified mechanic to review the vehicle and give you a report. If your serious about a car but unsure of it'* mechanical shape, it'* worth the money, IMO.

being able to tell if the car was garaged or not is pretty important if you consider appearance important.

I think its safe to assume that most newer used cars are either former leases, corporate vehicles, or people that trade in every 2-4 years anyways. I think it would be rare to find anyone in those groups that even cared about breaking it in; it'll be under warranty for as long as they own it and after that its not their problem.

By the same token, the "break-in" on a car isn't as extensive as what it used to be, nor as critical. If the car is running normally when you go look it over, then it'* normal.

Old days, "break-in" was for the iron rings to seat on the cylinder bores, flat tappet lifters to seat on the cam, transmission/differential gears to mesh together, etc. Stuff that took a few hundred hours of use to make sure it was working right.

Now days, moly rings seat within the first hour or so of use, and the rest of the tolerances are pretty much pass or fail before they leave the factory (And they fire all the engines on natural gas at the factory to test them out.) Not much to "break-in". Roller cams are pass or fail as soon as the oil pressure comes up the first time. Checking the oil for any flakes in the metal after the first few hundred miles is just that..checking to make sure the bearings aren't in the oilpan, otherwise there'* nothing to do.

All of the cars that I have bought recently (Bonneville, Town and Country) have been program cars (i.e. were part of rental fleets).

I am sure that they were not broken in properly.

Yet they had the remainder of the factory warranty on them when I bought them, so I had something to fall back on.

Of course you could drive a new car off the lot that ends up being more problematic than any used car out there.

Well you can almost guarantee that NO rental was broken in, but like curt said, theres not a whole lot, if anything in newer engines that require an extensive break in period. Same thing as that myth that you can't run synthetic oil in a brand new engine because the rings won't seat...its just not true anymore.

Still supposed to break it in for the first 500 miles, never hurts, just not as crucial.