Already providing Internet access in Avis' rental car fleet, the Autonet WiFi Router turns any equipped car into a rolling WiFi hotspot. Unfortunately you'll still need another device - such as a cell phone, PDA or laptop - capable of bringing the Internet into the car. But then anyone within WiFi range can use that connection just like at your local coffee shop, at home or at work.
Pricing for the drop-in unit is a bit curious: the router itself costs $595, but there is a $39 monthly access fee. Why, exactly one would pay to access their own router over their own - separately supplied - Internet connection, is a very good question, and one not answered by the company's materials.