Zipcar and Hostess Brands have joined forces on a sweet treat for National Chocolate Cupcake Day (Wed. Oct. 18). Together, the two companies have created a CupCake Car shown below, along with a national Twitter contest that will land one lucky winner with a year’s worth of Hostess Chocolate CupCakes if they correctly guess how many chocolate CupCakes can fit into the CupCake Car.

The Twitter contest is open to Zipcar members and non-members nationwide. To participate in the contest, a tweet must be sent using #BuckleYourSweetBelt between Tue. Oct. 17 at 12 a.m. EDT and Thu. Oct. 19 at 3 p.m. EDT. The winner will be selected by Fri. Oct. 27 and notified via Twitter, leaving a year’s supply of chocolate CupCakes just an educated guess away.

The special Zipcar, a Ford Focus Hatchback named “Hostess Chocolate CupCakes” is available for reservation by Zipcar members living in or traveling to Boston from Tue. Oct. 17 through Thu. Oct. 19. The vehicle features a chocolate brown exterior topped with a 3D replica of The Original Squiggle® and the interior is complete with a white fuzzy steering wheel cover, fluffy seat covers, and a chocolate scented air freshener for those with an incurable sweet tooth.