Sign into the Zipcar mobile app and visit your account page. From there, select Driving Credit to view your current balance. To redeem a promo code, select the + icon in the top right of the screen. Enter your code, click Redeem, and the driving credits will be added to your account.
Visit https://my.zipcar.com/book/billing and sign in to redeem your promo code. Click Add credit, enter your promo code and click Redeem.
To check your driving credit balance, view the top right-corner on your account’s Billing page.