Zipcar has announced that it will now be offering memberships to its car sharing service at the rate of $6 per month, not just its annual $60 membership. This is likely a response to the reality that car sharing is getting more competitive and the fact that Hertz is entering the market, and doesn’t require any membership fees. The new fee structure also allows someone to add an additional member to their account for $3. This greater flexibility will be helpful in getting more people in the door for Zipcar, though also points out the potential that the company is not just facing more competition, but may be hitting some snags in adding new subscribers with its current fee structure.