Purchased New had it serviced at the dealer and has always had this knocking when engine is cold. The dealers and the Toyota head office tech representative say it is PISTON SLAP and it is normal. The knocking is getting worse as more miles are on the vehicle. Piston slap is a serious problem in the long run. It can cause rings to break, scratches in the cylinder and much more problems. I expected the car to last to 200,000 miles, I do not think it will, private mechanics do not like the sound of the PISTON SLAP. Every time the engine is cold I have to run it till it is warm before driving it. Its a pain in the ...

Not to my expectations of a TOYOTA.

Update from Mar 13, 2014: 95,000 miles Piston Slap still a problem. Engine sounds like a Diesel engine. Toyota says its normal. It takes 15 minutes of warm up for the noise to go away. Normal????, if its normal then they designed it to have piston slap and all would do it. Toyota does not back up its products. If you must buy a Toyota good luck and I recommend you purchase an extended warranty.