Without rental cars, people would be forced to take cross-country road trips the old-fashioned way, via covered wagon or piggybacking on Paul Bunyan. Steer your own ride with today's Groupon: for $20, you get $40 toward a car rental from Avis Car Rental, valid at more than 2,100 locations in the United States and Canada, excluding Alaska. Rental rates and vehicle availability vary by day and location; consult the Avis online reservation system for estimates.

Avis Car Rental lets vacationers borrow four wheelers from an extensive fleet with sizes, makes, and models fit for trips of all types. Mini Cooper and Chevy Camaro convertibles let down their tops to reveal stellar views of coastlines, desert plains, and palm-frond canopies, and full-size four-door sedans such as the Chevy Impala comfortably transport the whole family. Camp-goers that require room to tote tents, coolers, and stowaway hitchhikers can accommodate wide loads in full-size SUV rentals such as a GMC Yukon, which seats up to seven passengers. Travelers can upgrade their wheeled steeds with helpful tools such as a step-by-step directions program articulated by Garmin's Where2 GPS navigation. Avis's e-Toll program allows voyagers to breeze through tollbooths in the electronic-payment lanes, skipping lines and eliminating the need to prematurely smash beloved piggy banks.