The robot itself is relatively simple, with four geared DC motors, motor drivers wired to an Arduino Nano that interfaces ... By connecting a Bluetooth controller to the smartphone and drive ...

[Labpacks] wanted to build a robot car controlled by his phone ... build a phone interface that will talk to your hardware over Bluetooth LE, USB, or Ethernet (including WiFi).

Arduino boards get a Bluetooth Smart dev kit from Nordic Semiconductor. The SDK is compatible with a range of Arduino, ChipKIT shields that employ the nRF8001 Bluetooth Smart connectivity device.