The engine or the alternator your car generates noise on the radio? This filter can be the solution! It is a sound-absorbing regulator being placed between the food and the car radio.
The filter is fairly small and has two incoming wires, yellow to red to ignition and battery, and a blue thread to exit. In addition we also have the black wire of mass.
There is an led and a relay to trigger the radio only if the ignition (Red wire) is on.
There is also a 10A fuse in fuse holder.
It didn't work very well for me, because the alternator noise is still present when the radio is loud. He reduced a bit the problem, but not fixed. I think I'm going to have to pull new wires from the battery to fix this defect. Anyway, I leave the link to the product: