vandergus The wltoys a959 12mm hexes are compatible with this car. And I would not recommend upgrading to a brushless motor. It's hard enough to keep the drive train up and running with the stock motor. Can't imagine doing it with more power running through. The car comes with a combo Receiver-ESC so you're not just looking at a new motor and ESC. You'll also need a new transimitter and receiver and probably a new servo.

vandergus From the photos it looks like two 18650 li-ion cells shrink wrapped. It is not lipo.

BG412039431 1) A physically larger motor require some customized mounting bit might be doable. You would need a new ESC, though, and this car has a combo receiver ESC unit. So if you put in a new ESC, you would need to put in a new receiver to be able to talk to it. 2) Yep, the wltoys shocks should fit. HBX also makes some all aluminum shocks for their 18 scale cars that fit. 3) You should be able to but I was having a real hard time getting the larger bearing out of my steering blocks. You need a 12mm x 8mm x 3.5mm bearing and a 8mm x 4mm x 3mm bearing for each wheel. 4) See question 1.

BG412039431 The front and rear drive shaft are 55 mm long. I replaced mine with the metal drive shafts for the Wltoys a959. They are about 3 mm shorter but have been working fine. I also had to sand down the cross pin a bit to fit in the differential cups. The car really needs metal drive shafts, though, so I would recommend the Wltoys parts.

BG412039431 The wheels have bushings but the main drive shaft and differential outputs are on bearings.

BG412039431 Most speed tests on these cars top out around 25 kph.

BG412039431 It would be difficult. The stock electronics have the receiver and ESC combined on the same PCB. A new brushless motor would require a new ESC but you wouldn't be able to connect it to the receiver. You have to get a new receiver (and transmitter) and ESC to make a brushless work.

BG412039431 It's a 5 wire servo.

BG412039431 It's a 2-pin JST SM connector.

BG412039431 The battery uses a 2-pin JST SM connector for the main power. It also has a standard 2s balance connector for charging.

BG412039431 I would not recommend this as a gift because of the maintenance required. I have a couple and they each required a few part upgrades to continue working. It's fine for me because I wanted a toy that would give me and my kids fun mechanical projects to work on. But if I gave one as a gift, I would be afraid it would stop working after a week and the kid would be left with a dead toy.

BG412039431 Maybe? The most difficult part is that the receiver and ESC are a single unit. If you put in a brushless motor, it would require a new ESC unit, which you could probably find a way to mount but wouldn't be able to connect to the receiver. You could also get a new receiver (and transmitter) and replace the stock receiver-ESC unit entirely but that's getting expensive.