Low Vibrations in CVT Transmission?
 

Hi Everyone: I bought a 2013 new Scion iQ a few months ago. It does everything I want it to do perfectly, which is basically be small and get good mpg. I live in the Bay Area, so having a small car is a must . It has a CVT transmission, which is new to me. I've only driven manual before. I noticed early on that the car makes a low humming/buzzing/vibrating noise at low speeds and low RPMs (20-30 mph, and under 2000 RPMs). The noise disappears at higher speeds. The car has two gear modes, a regular D and a "sporty" S. The S mode basically cranks up the RPMs higher for slightly more power. The noise only happens while in D mode - never in S. I took it to my Toyota dealer for its 6 month regular check up and I requested to drive with their lead engineer. He listened and told me that it "perfectly fine." He said the CVT is "underloading the engine" which causes the vibration at low speeds; basically the CVT's computer is trying to match a good rpm ratio for my low speeds and it sometimes can't match it. He assured me that it's not a problem and my engine/transmission is perfectly fine. I don't know much about cars. Hence my question. In your opinion, is this okay? The Toyota technician seemed perfectly zen about it saying that it's not a problem and it's not something that can be "fixed." What are your thoughts? Thank you!