Comment by hondadriver

Disclaimer: I know little about the technical details of cars.

I don't know if it is the same noise, but I had a loud, fast paced, 'whoom, whoom, whoom' sound on my Honda Civic Hybrid from 2008 when going downhill a lot.

Living in the Netherlands (mostly flat) I only had this during holidays in less flat parts of Europe. Never thought much of it and when asking the dealership they never heard about the problem, but also could not see anything wrong with the car. And it only was reproducable in mountain areas, and took a while to surface...

Then after about 3,5 years, after a holiday, the sound was almost always present. Drove to the dealership and the brake discs needed te be replaced, they were 'square'.

I was not allowed to drive another mile (kilometer in my case ;) with the car.

I always brake as less as possible going downhill, and always use the L (low) gear position, but can't prevent it. The roads in the Swiss Alps are so steep, only low gearing does not help, at least not with a Civic Hybrid. I don't drive with my foot on the brake all the time, but pump the brakes when really needed.

(in comparison, the Seat Ibiza Diesel car I had before could slow down a lot better in low gear, almost no braking was needed, but when going downhill with the Civic in low gear, it goes faster and faster, until you just must brake. Also the Ibiza was manual gear, like most cars in Europe, the Civic had a CVT)

The dealership thought it could be a result of the brakes getting hot when going downhill (cannot be prevented) and then keeping the foot on the brakes when standing still deforms the braking discs.

Using neutral gear position and if needed the handbrake when stopped, could be prevent it from happening again.

After replacing the discs I drove the car another 1,5 years until October 2013 and never heard the sound again.