Vehicle update for anyone wanting to hack an RC car like this. Good news/bad news.
New Bright changed their PCB & circuit design a year or more ago. The discrete H-bridges are long gone, so the info above doesn't apply. The new ICs are proprietary and difficult/impossible to hack. On the bright side, you can buy an MX1508 dual H-bridge for just a dollar or two on ebay:
https://www.ebay.com/itm/273757254762 My previous comments and that article only used the H-bridge portion of the original PCB anyway.
Info on the MX1508 at
https://www.instructables.com/id/Tutorial-for-Dual-Channel-DC-Motor-Driver-Board-PW/ and truth table attached.
In a related story, Walmart has new $10 RC vehicles (their own house brand "Adventure Force") which are a great hacking candidates. Photos attached. These have several noteworthy improvements over the original New Bright vehicles (which are getting scarce anyway):
1) the Adventure Force (AF) vehicle assortment uses a modern 2.4 GHz radio control system (no external antennas) whereas the New Bright (NB) vehicles use decades-old 27 and 49 MHz radios with clunky external wire antennas. Even if you remove the PCB and use just the mechanical chassis, save the RC system for a future project.
2) the steering mechanism in AF vehicles has better torque and steering range than NB vehicles, although one of mine was assembled wrong and needed to be fixed.
3) the AF PCB uses a SMT
(WAIT FOR IT!) MX1508 dual H-bridge! Yes! You could tap into the inputs and connect your micro to the PCB.