How do rental car places count their miles?

I'm going to be renting a car for a week in June and driving from Maryland to Boston to Pennsylvania and back to Maryland. Enterprise says I can have unlimited miles if I keep it in Maryland or it's bordering states. But if I leave the bordering states I'm allowed 200 miles a day plus 25 cents for each additional mile.

Is there a way that they can know how many miles you drove a day, or do they just calculate it when you get back? If I have the car for a week and I'm allowed 200 miles a day, then I'm limited to 1400 miles. But my trip should be less than 1000. So even though I drove more than 200 miles a day should I be able to trick them with the final mileage?

Brian

Problay by the mile I would say and it very cheap then they put it how much for hundred or somthing like that or find out yourself they will tell you what they do.