Isolated power supply for measurement
ESD doesn't "just happen". Use sufficiently isolated cable, so that a spark wouldn't even get to the cable. 

EMI might be interesting; you'd need shielded cable against that (but also, a noise and signal model. Wild guess is that your potentiometer's signal has a few Hz of maximum frequenzy, whereas your EMI would have kilo- to Gigahertzes and can very easily be filtered out – like you'd filter the output of a potentiometer, anyway, since you don't want to deal with the "scratching" of the pot, anyway). 

But then again: there's plenty of electronics in your car. So digitize your potentiometer reading as close to the sensor as possible and send the values over a digital link. Hint: CAN bus was invented for car-internal communication, and there's a lot relatively cheap microcontrollers who can do that. I'm pretty sure you were planning to buffer / amplify the potentiometer sensor output right at the sensor, anyway, so why not directly convert it to digital there?