Comment by bluGill

Every try to do that?

The cost of a rental car for a week is high - you can pay for a lot of gas for the cost of renting a car a few times a year.

More than one person I know has tried to rent a car and discovered they didn't have any on the day they went to pick it up. If your car can make the trip you avoid all the issue.

Note the above is about road trips. If you are flying (or taking the train) someplace than you will rent anyway (or have some other plans). However one of the advantages of road trips is you take your own car.