Changing the receiving frequency of a cheap RC car
Given this is the ONLY RF circuit, but needing only 100 foot range, we can trace out the circulating-RF-resonance-path. I think its

C4 -- L3 -- Cemitter_base -- C5 

and

C4 -- L3 -- C2 -- L2||C3 -- C6 

but note the series LC to the antenna. With the car's antenna out in free-space.

C3+R2 likely are the super-regenerative quenching-oscillation time constant, thus C3 is
a timing capacitor for 100,000 Hz explore-the-RF-power-level behavior.

Looks like there are THREE resonant LC circuits: 2 of series (L3,C4 and L1,C1) and 1 of parallel (L2,C3).

The Q of L3,R1 (5.6uH at 30MHz => Z of ~~1,000 ohm, and 560 ohms) is about 1 or 2, so no frequency selection occurring in the emitter.

If C4 is a huge value, then a possible LC resonance is the L3,C2.