If you are paying by time and not the time of day it really shouldn't matter. I never trust a clock I don't know is right, I'm one of those people who have five clocks on my desk (I love clocks) and they are all set to the exact same time.

If they are saying an hour is 60 minutes, then I don't care what time the card says. If however, they are saying an hour is 56 minutes becuse they have different time settings on entrance and exit, then it's a totally different issue.

I figure I get even with them when I'm in baggage claim at 58 minutes and prepay my exit to get the 30 minutes grace period instead of paying for the second hour