Techniques | Pothole effect

I've been trying out a more realistic approach moving my 4x4. I want to imitate the vehicle driving down a bumpy track. The problem is that the wheels are a parented to the body so they move wherever the body does. Ideal if you just want to move them around relative to each other but I would ideally like to animate them separately to add another sense of realism to my animation. The video above illustrated the problem I'm having.