In Super Monkey Ball 3D for the 3DS, there are several cars you can unlock by performing certain tasks. Here are the cars you can unlock, and how to unlock them.
Flying Carpet – Beat the record on track 2 of Mt. Tyrano
G Catepillar – Beat the record on track 1 of Mt. Tyrano
Kitana – Beat the record on track 3 of Sky-Way
Mini Shooter – Beat the record on track 2 of Sky-Way
Mr. Magic – Spend 20 play coins on the vehicle select screen
Robotron – Beat the record on track 1 of Sky-Way
Super Tops – Beat the record on track 3 of Mt. Tyrano
Play coins are earned by leaving your 3DS in sleep mode and walking around. The 3DS has a motion tracker that counts your steps. It only takes about 100 steps to earn a point, so put your 3DS in your pocket while you’re walking around and you’ll earn them fairly quickly.