 Toyota's  bigger 4 cylinder engines have a higher frequency of a problem now. The issue is called a "COLD START RATTLE". Because our EPA has mandated cleaner & more efficient vehicles, the top end of these motors have many more moving parts (VVTI) The common problem now (with other brands too-Honda, etc) is a 1 second metal on metal "rattle" that occurs only at cold start (lack of oil to small moving parts in the VVT). It's loud /very noticeable and makes one wonder how long before the rattle progresses or wears out internal moving parts (ruins the top end or all of the engine). My Camry has this problem. My dealer acknowledged the problem and was instructed to replace (1) cam and did.. It did NOT solve the problem. Took it in again (Vancouver, Wa Toyota) , they kept it for a week (agreed it was still an issue) and sent me home with my Camry that still has the same pronounced cold start rattle. Dealer should have done the right thing and backed a customer in my opinion. Ours is a 2012 model with the 2.5liter & 40k on the car. Rattle started about 25k mi. I'm original owner and car has been serviced better than recommended. No changes made to engine on the new model/2015-exact same design. I submitted a Lemon Law claim to the factory and they simply denied my claim with no reasoning stated. So, needless to say, I'm an unhappy camper. Can't sell it in good conscience, can't keep a car with a flawed engine.  Read the forums, it's a fairly common problem on the 2.4 liter, 2.5 liter and 2.7 liter. So, I can't recommend the car. I do recommend the hybrid Camry however and should have bought one-fabulous car, different config.  Thanks, a seasoned Engineer