rheostat for led's in a car

I'm trying to find a rheostat that can dim the LED's in my car. The stock rheostat in the car doesn't work with LED's and they are a little too bright for comfort. What is there to buy that would dim 12volt LED's?

A PWM controller - a 12V motor speed control is perfect.

Thanks! I'll look into that, or if you have a direct link to one please post it.

Here is a simple circuit controlling the LEDs PWM.

**broken link removed**

The frequency is 2.8KHz. If you want e.g. 280Hz just replace C1 by 100nF (now 10nF)

Note: 100% output will be at the lower end of RV1. The circuit controls from zero to constantly 100%. Adjust the current limiting resistor (R3) according to the requirements (no of LEDs in series for instance).