I see this one some radios. What is telementary?

Telemetry is data feedback from the car to the radio. Temperature, voltage, speed, etc can all be included in telemetry data.

Review, experiences and comments with the system from RCTech members -

http://www.rctech.net/forum/electric...appointed.html

telemetry can be nice for nitro/fuel powered cars, so you can see your engine temperature without having to go to your car to check and also to check the voltage of your receiver battery if you are racing for long periods of time.

if you race electric cars you may want to look more into data logging. this is when you put a special piece of electronics (called a data logger) in your car that measures and remember information until you stop and connect the data logger to a computer and check to see what happened. this can be more complicated if you are new to electronics and wiring but provides a lot more information since it actually stores it instead of just showing you what is happening at that second on a screen which is what telemetry does.