Bumper to Bumper warranty means that they will fix defects or norma wear and tear. you backing up onto a curb is't normal wear and tear, neither are road hazards and improper driving. If the bumper just fell off, that would be a defect, if you cause it damage thats your problem.

 

The only noticable change you can see is in the VVTi. VVTi work off direct oil pressure. It probably won't be noticable to you, only if you had a dyno. The possibly you're just noticing it now because of mental image of a non-new vehicle.

 

The cheapest way to try and get your bumper fixed is to try and find the paint repair guys that go from dealer to dealer repairing paint chips and such created during shipping, test drives, and even an occasional mistake from the factory. Several years ago my wife backed out from a Sonic Drive-in stall and was hit. She had the dent popped out asap but it still left a shallow crease and the paint was damaged. The reapair shop said they couldn't fix it. We would have to buy a new bumper cover and have it repainted which would have cost several hundred dollars. I found the repair guy and he quoted me $80 to fix it and repaint the whole bumper. Not bad. I know it sounds cheap but this is the guy the dealers trust to fix the car so that it looks perfect and will last at least long enough so they don't have to fix it under warranty.

 

They *might* have put a different weight motor oil in than what you had before. To check it you can buy an oil viscosity tester which is sort of like a big spoon that has a string hanging off it. Drain a little bit of oil into a pan, use the tester, and see if its the appropriate oil weight. Or you can do the "poor man's oil viscosity tester", which is to take out the dipstick and see if the oil drips off it faster or slower than normal. You have to know what normal is for that to work, so maybe compare to another dipstick on another car that you know has the right oil.

I had an oil change place once not get the airbox back together right after opening it up to tell me I needed a new air filter (when in fact I did not need a new one). Suffice it to say I didn't go back. And on another occasion I had a different oil change place overfill the car by about a quart. Was overfilled on dipstick, not just on the invoice.

So you could check for things like that too. Its not impossible they messed things up.

As far as thinking you hit a curb... umm, if you file an insurance claim, you'll have to pay your deductible first. But everything above and beyone the deductible will be the insurance company's bit. And you could expect you premiums to go up too, since it would be your fault.