I have tried a number of things, some worked some did not. Here is what I know so far.
The greatest reduction in road noise came from soundproofing the doors. Remove the plastic door panel. One screw in the armrest hole, one screw in the door open lever. One pushpin in the side of the plastic by the door latch. The plastic just pops off use a flat blade screwdriver to work your way around the door. The door open lever pulls off easier if you loosen the plastic around it. It moves to the side and out. You will need to pull fairly hard on it to get it to let go.
I used 3M brand spray glue to attach the sound proofing to the inside of the plastic. You can use little bits to fill the spaces you dont need one perfect cut. I removed the foam block by pulling on it and replaced it with soundproofing.
Do this for all 4 doors and you will like the results.
Sound proofing the wheel wells did not do a thing. I think that the high-speed road noise is transmitted through the axle brace (the cross member thing) into the car. No way to change this.
I used 3M extra strong spray and soundproofed the under carriage. With the exception of noise transmitted through the front axle into the frame, this eliminated road noise. The material I used does not hold water so no problems with creating rust. Keep it away from the hot exhaust pipe. The exhaust is shielded so just but the stuff up to the shield. This takes time and you should invest in some car ramps. Jack stands work but ramps are safer.
Soundproofing the hood did quit hard acceleration a little but was not worth the effort.
Putting soundproofing under the rear seat helped a little. (It just pulls off straight up tug hard).
A mat over the trunk side of the rear seat helped, as did covering the rear trunk side deck.
So, I have this connector flapping in the breeze and I'm wondering if anyone is able to tell me where this connector plugs in? The connector on the gasoline side of the engine compartment under the brake solenoid. Please help.o
I have a 2016 Prius IV with some very odd climate control issues. Up until about a few weeks ago the climate control worked normally. It came on immediately when starting the car to the last preset and worked as it should. Now the climate control takes about a minute to show anything on the...
I am particularly interested in the following August 2009 post by Phoenix:
"As for the whine, our 2002 Prius makes a whining noise at a specific speed (can't recall, but I think it's about 40-45 mph) that comes out of the hybrid module. It's not noticeable with the air conditioner or heater...