It's easy, it's typically free, and it often comes with perks like free upgrades and the ability to skip the lines. If you're a frequent car renter, it's well worth the five minutes it will take you to sign up. As a member, most companies will store your rental preferences, guarantee vehicle availability with two hours notice and give you rewards points you can redeem for free rentals or upgrades. And many loyalty programs will also carry over your status from another program, so if you're able to secure elite status from one company, you'll likely be able to transfer that status over to another. Check out small-business benefits programs like Hertz Business Rewards or Avis Corporate Rewards, as they offer a percentage off every rental if you register yourself as a sole proprietorship.