If I'm shooting ahead of the car there is usually little, if any, blur indicating the movement of the car. Here's an example from Fanshawe Road in London taken yesterday when we were on our way to see Tron: Legacy.
The motion is very visible in this shot that I took along Highway 2.
On the other hand the effects in this photo are ones I added from Picasa - heightened contrast and soft focus around the edges.
There was a sad surprise during the drive yesterday. I've taken many drive-by shots of Sunny Acres on Highway 2. Here are two from October of last year.