Is this possible?
I have an electric car.
I want to adjust my radio so that, if I bury the throttle it dosen't actually use the motor's full potential, maybe only 1/2? Just wondering which radios have this option. I just dont want people to go full speed if I let them try my car.

It's called End Point Adjustment or EPA. Also referred to as "ATV" on some radios. Most newer radios have it. The Airtronics MX-3 is a nice radio that has that function. Hell, even the cheapy radio that comes with the RC18T has it. What radio do you have?

The the radio I got from the RS4 RTR, so its pretty old.
The EPA wasn't really effective, it didnt really limit power much. Perhaps the radio nowadays have a much better EPA?

No, newer epas are not diff. I don't think there's a good way to do this - limiting by epa still lets esc see full voltage and that's the prob - why you are finding it not effective. Will make esc run hot.

Only way I'm aware of is thru esc programs made to reduce speed - EVX has something like that for example. Other way is to reduce voltage (diff pac).

Why are you risking letting others drive it anyway?. I don't share mine - letting someone else drive is great way to get it broken. I just tell someone thats asked its way expensive and they can't afford it.

I’ve done the throttle EPA thing with many radios & cars, old & new. Always worked great, could always turn it down more than enough. Have an old Magnum Jr. with external knobs that I can pretty much turn unnoticed as I hand it over, very slick.

Surprised it’s not working for you. Perhaps try turning the EPA all the way up, recalibrate your speed control, then try turning it down. Maybe it has a limited adjustment range, and the speedo was already set to the lower side. (assuming you're not confusing EPA with trim)

Duster, you are right directionally, it’s a less than ideal condition for the ESC efficiency and heat wise, but I wouldn’t get too concerned. I mean, we are only letting the noob loose in a large flat area with limited obstacles, right??? Overall load should be fairly reasonable then, with reduced power & speed, any decent ESC should be fine. At least it always has been for me.

Cheers