Just finished renting a van here. The trip mileage started at 10, Trip mile i checked using google maps for the route i took says 22. Trip mileage i came back at says 32.
You need to check the mileage with them and not trust them when they write the out mileage. Plus, when you check out the car there's no where they write the out mileage. They decrease their out mileage record on your receipt and when you come back its higher. There is absolutely no way to say anything about it though because obviously when you finish the rental its already in the receipt and when you come back you can't show them where you exactly drove so it's pointless.