Jim:

No 459 mhz is not explicitly designed for ground vehicles ..it is still totally ok to use this frequency in model aircaft.

At the mo I have 2 reftec UHF transmitters that work...1 receiver and 1 (much better quality) multiplex Tx and Rx that works great ..all on UHF 259 Mhz and allowable in model aircraft and bots.

One day I will get round to using it in a bot but at the mo we are having no probs with 40 mhz.

Tom