Hi, we have a 98 V70 AWD that has been producing a loud rattling that is speed sensitive. I can hear it on the freeway and notice that it slows down with the car as I come to a stop. It was intermittent at first, but in the past week has been pretty consistent. The sound appears to be coming from underneath the car, toward the rear.

I also noticed just in the last few days that the rear of the car will occassionally have some very noticeable vibration.

Gas mileage has been very poor lately and I had my lower engine mount replaced not too long ago. Upper engine mount also needs to be replaced.

Had a bad rattling problem before with the exhaust when car was in idle, but that was fixed with some spot welds on the loose hanger.

I plan to take the car in but would appreciate any input so that I don't go in blind.

Thanks in advance!