A few weeks ago, the Avis Now app showed I had a Linc/Caddy of some sort with 2x miles on the clock. As I pulled out, I was on the phone but remembered thinking it didn't feel that fresh. I remembered to look at the odometer a bit later and it was 11,x3x. I don't know how they can manage to get it off by >10k!
I had a similar issue on Hertz a few weeks ago where it was off by 8k. it was 18,xxx instead of 10,xxx.