Actually, 7 day/60 hour and 8 day/70 hour limits are DOT rules, it's just UPS has never used during the 8/70 rules for package car drivers before, that I'm aware of.
Just remember, as drivers, you're responsible for keeping track of your hours, and violating carries really steep fines if the DOT finds out. UPS also gets the fine too, which is probably the only reason they monitor your hours. But don't rely on them.
Just remember a few things: you can reset your hours to zero only after having 34 hours off; if you're running a 8/70 schedule, you have to have 10 hours off between doing shifts, and your meals and breaks don't count towards your total hours, provided you aren't working thru them. You can only drive for 11 hours in one shift, and with a few, unforeseen weather exceptions, you can only work 14 hours, from punch-in to punch-out, and that 14 hours DOES include your meal and break periods.
So in package car, your 14 hours starts at your start time until you punch out. And your 11 hour drive time starts when you get the vehicle moving in the morning until you park it at the end of the day, minus your meals and breaks.
For example, if you start at 8:30AM, and leave the boxline at 9, deliver all day, and take a 30 minute lunch and a 10 break, your drive time is up at 8:40PM. By law, you can't drive again until you've has 10 hours off. They have to come get you after that.
This happened to me once in feeders a few years back when the interstate I was on got shutdown for over three hours in a blizzard. On my way back, my 11 hour drive time ran out, and I pulled over and waited for them to come get me. I ended up being on the click that day for over 18 hours.