XRAY - Model racing cars

If your radio isnt that powerful, there isnt much to be done other than having a external antennae.

You could try to make a custom mount to use a 1/12th scale pan car roll over antenna?

2.4 wavelength antennas is half the length of AM/FM radio gear. 2.4 can be mounted at the horizonal position with some interferance, but it is cleaner. AM/FM radio gear has to be mounted at the vertical position for it to be efficient, must use the complete length of 14"s. you may mount it horizontal, but cuts down on distance, maybe 90%. less than 40sqft or less. Bashing a differant story.

Cut the tube for length you need for the antenna. You usually need 1" or 26mm exposed to the air.