I saw this product somewhere about a year ago and in lieu of purchasing it, I put a modified form of the idea into daily practice with Katherine. When we get to the car I have her put her hand on the rear tire while I open the door for her so that she can then climb into her carseat by herself. Again, when we are getting out of the car I take her around to Jack's side of the car and have her put her hand on that rear tire while I get him out.
Katherine cooperates most of the time, but I think the Parking Pal, reviewed over at SIMPLE, would be a more visual reminder for both of us. I think my favorite is the FishPal design, but the FlowerPal and the DynoPal are pretty cool as well. What a fun way to keep kids safe!