I recently had to trade in my 2013 Prius 4, at 177,000 miles because of a blown head gasket as well as needing 2 rear wheel bearings... dealership quoted $7000 in repairs...to start. I found a 2015 Prius 5 with 60,000 at another dealership the following weekend, and traded in the old for the newer model....3 months ago I had to replace part of the steering wheel shaft on my 2013 Prius. On this 2015 Prius 3 weeks after purchase, I started hearing a similar clunking sound down my the brake pedal...the service department at the dealership said the steering column is starting to fail on this one as well, at a cost of $4300.... the 2015 steering wheel doesn't have any slop or play... like my 2013 Prius did. Currently there's 66,000 miles on my new car. Thoughts? I checked for any tsb's or recalls on the Toyota website.
Did you get a 1 month warranty on the car? Your 2013 probably had a intermediate shaft replacement. If your 2015 doesn't have any play or slop, it might just be a suspension related problem. Clunking noises can come from worn endlinks or worn bushings on lower control arms. Did you run a carfax to make sure the mileage on the 2015 is original mileage?