I've used systems with telemetry before, for both nitro and electric vehicles. I didn't even bother with the speed, but I thought the temp sensor was useful, both for nitro tuning and electric motor gearing. We checked the temp sensor readout vs a handheld temp gauge and the largest difference we saw between the two was 3 degrees Fahrenheit, so the accuracy was pretty decent. The receiver battery voltage was also useful. Just don't try to check the readout on you radio while you're driving
