I'm a new TCH owner. I checked the speedometer reading against the mph reading on my Garmin C330 gps system and noted a 3 mph difference at 60 mph. That's 5%. Anyone with the same problem? The most I have on my Avalon and Highlander is a 1 mph difference. Also, has anyone added aftermaket leather? If so, what was the cost and are you happy with the aftermarket leather? Thanks for your time.