car dealer put 4,600 miles on car in 15 days

I bought a car from the centennial Chrysler jeep by my house in aurora co. I went in there on September 28th and was approached by a salesman. I told him that this was my first time buying a car and and didn't have enough credit to get a new car so he showed me a used 2008 Honda civic. After I test drove it I decided that I wanted to buy it and signed the paperwork for the loan. After about a week of driving the driving the car i started to notice that it shook more than it should at idle i looked it up online and read that it was most likely the motor mounts. I knew this wasn't going to be covered by the warranty so i started to save up the money to take it to a shop. After about six weeks,on November 12th i brought it in to make an appointment for Monday the 18th. I still didn't have enough money to get it fixed so i took it to them anyway because it was shaking so bad the foor panels were rattling and explained to them that it had been shaking pretty much the whole time I've had the car. They told me that there was nothing that they could do about it because the motor mounts are outside of the engine. I was pretty irritated that they they weren't going to fix it because because the car only had 78,366 miles on it when it bought it, the motor mounts shouldn't be bad on the car yet. I picked up my car and and went home thinking that i was going to lose the car because of how expensive it was to replace the motor mounts, a shop was going to charge me $671 to replace two of them.
On the 28th i found a paper that said that when the dealer did the certified used car inspection on September 13th the car only had 73,762 miles on it. Which was weird because 15 days later when i bought the car it had 78,366 miles on it. I went back into the dealer and brought it up to the sales manager and all he had to say was that his "trained technician" must have wrote down the milage wrong on the checksheet. I looked it up on carfax and the "trained technician" had actually written down the correct milage and the really did put 4,600 miles on the car in the fifteen day period that they possessed it. I'm going to be talking to a lawyer about it on Monday to figure out what i can do about it.
Does anyone know why the dealer would have to put that many mile on a car that fast?

I wish you luck, But as you said you did not buy the car until Sept 28, The amount of mileage put on the car before you bought it is irrelevant..........unless you can prove tampering

Attorney is gonna cost you a lot more than motor mounts!