There was an interesting bit of news on Sunday from Hertz CEO Mark Frissora, saying that Frissora considered buying Zipcar before deciding to roll out Hertz’s own car sharing service. Over the last few months the car rental giant has been adding cities for the Hertz On Demand hourly car rental service. There are a few reasons why this could be real competition for Zipcar. 1) Hertz has a fleet of 375,000 cars, 30 times the size of Zipcar’s fleet. 2) There’s no annual membership (Zipcar charges $60 a year) 3) Hertz can market to millions of customers who already rent their cars. The only reason for Hertz to have bought Zipcar would have been for the brand alone since operationally, Hertz has more infrastructure anyways. Hertz made the bet that the value of associating a brand name with car sharing just wasn’t enough to warrant an acquisition. We’ll see if “On Demand” is enough of a pull to get drivers to start using Hertz’s hourly rentals. And for folks to forget the days when O.J. Simpson was the face of Hertz Rent-A-Car.