For the first time today, I had the following problem:

Turned the car on, and put the car into reverse. All of a sudden, the gas engine started revving up in cycles. It kind of sounded like an old truck that starts humming louder during warm up. I wasn't sure if the revving was getting harder or just maintaining a really high frequency, so I shut the car down. Started it up and left the car in park, waited for the gas engine to initialize. As soon as it did, it went right back into the high revving cycle.

Shut it down again. Waited, started it back up. Drove without problems for the rest of the day.

Any ideas what that was about?

 

Mine has always done something similar, almost sounds like a diesel engine when you start up.