10 seconds! lol. you could pan 20 cars at once in that amount of time. to do a panning you want to have your shutter speed somewhere between 1/30th of a second and 1/80th of a second depending on the speed of the car. I was also confused on that before I bought a DSLR but as soon as I tried it, they started turning out perfectly.
but I own a D3200 and yes, it's excellent for doing pannings. here's a few of the ones I've done over the Summer with my camera.