Yes, any one year old car with over 40,000 km is most likely an ex-rental. You can get ex-rentals with under 30,000 km, so keep an eye out for them. Some rental companies dispose of their cars at lower kilometers.... Hey, bottom line, nothing wrong with an ex-rental.
There are not likely to be many one-owner 20,000 km Sonatas sitting around on dealer lots.
Happy shopping.