Take the car back, and demand that they keep it until the problem has been fixed. Most likely the wheels just need balancing or something like that. I've had a TL from new for 2 years and I never had this problem.As for the gas peddle it may be different from other cars she has driven before. The TL has a drive by wire throttle system, the peddle is not physically connected to the engine like on most cars. When you do stuff with the peddle, it talks to the computer and the computer tells the engine what to do. For example if you suddenly put your foot to the floor, the computer does something different than if you slowly push down.Also unlike most cars the peddle is anchored at the bottom, like a BMW or Porsche. This can take some getting used to too, especially if your wife has small feet. The ball of her foot may be closer to the hinge and therefore the peddle may seem different than on a regular car.So I think that the likelihood is that the car is fine, but needs a wheel balance.