road noise increases with car speed and at 70 mph can't hold a conversation
what causes excessive road noise on 2001 Toyota Echo
I just had the same problem with my 2000 Echo, it turned out to be the transmission for me... I had already replaced the front wheel bearings and CV joints... When it is making this noise, at 70 mph, take notice and see if the noise gets louder or softer in curves, if the noise changes while turning, you have bad bearings... If there is no difference in the sound, most likely you have a bad CV joint or bearings in the transmission going out...
I just bought an 03 Echo from a dealer, who serviced the transmission, and they said the Echo is noisy because Toyota did not put any insulation. I was thinking about taking the carpet and back seat out and painting with bed liner paint, or expanding foam, or regular rolled car insulation then reinstalling the carpet. I havn't decided yet. Mine sounds like a small airplane and seems like the sound is coming from the back of the car.