18650 for my remote car?

Bought a 20buck toy car. It was fun but too bad the battery life was shitty.

It is a 500mah 4.2v battery pack made of 3 batteries. I was thinking whether I can use my 186500 battery as it wrote 2400mah 4.2v?

Anyway I feel quite funny that 3 battery only have 500mah. Does it mean one battery has 130mah??

Yes, you can use a 18650 since the voltages match.

The 3 battery pack is in series (1.2V each), so it is 500mAh each battery.