High Revving sound on cold start on the corolla and experience on the nissan versa 2011

My toyota corolla is now 2 years plus old and just two weeks ago, it started to have a high revving sound at the end of a cold start after the tachometer goes to between 7 and 8 k range. Subsequent starts does not seem to have the problem. So, I send my car in to the dealership last friday so that they can check the cold start on saturday. Renting out the Nissan Versa 2011 for the weekend proved to be an experience. Comparing the versa 2011  with the corolla 2009, the corolla automatically turns on the head lights by itself but for the versa, I have to manually switch on and off the head lights. There is no vanity mirror on the driver's side for the versa as versus the corolla. The versa also does not have temperature indicator or meausres the average miles per gallon. There is rear windscreen wiper in addition to the defroger for the versa while the corolla does not have the wiper, only the defroger. The versa does have the power windows and power lock as the corolla.  The corolla has more space on the glove boxes compared the versa. The versa is suppose to be a smaller car compared to the corolla though the driver compartment seems spacious enough. Compared to my corolla when it was new, this new versa seems to have an engine that makes more noise. The ride on the versa seems to be floating along while cruising at 60 plus 70 mph compared to the corolla. Calling the dealership on the following monday, I was told that they narrowed the problem to the VVT gear and changed it. I was told that many people had the same complaints and it was covered under warranty. Thank God!