[volsfan0911]

I thought the Jetta TDI seats were great. But I WANT the headrests pushing up against the back of my head - that's the whole point IMHO. That way you can relax your neck, have your head in the correct position and enjoy no neck muscle fatigue. Plus, as I work at one of the level I shock/trauma centers in Baltimore (Hopkins) you WANT the headrest limiting rearward movement of your cervical spine (a.k.a. whiplash) after impact in a severe frontal impact. The forward-most point of the headrest is designed to be at the middle (rearward most sticking out) point of your skull.

 

[volsfan0911]

Yes, it makes sense but I thought whiplash was the head jerking forward and back. I think the newer Jetta/Golf are introducing active headrests which follow your head, that seems to make more sense.

Whiplash (a.k.a. cervical hyperextension, etc.) is exactly that. You're driving at 30 mph, hit something in front of you (e.g. another car) and decelerate VERY rapidly. In English, you go from 30 mph to 0 mph almost instantly. Problem is Newton was correct and "an object in motion tends to stay in motion....". This means YOU are still going forward when the car has suddenly stopped. So your body mass gets slammed into the seat belt (hopefully you're wearing one!) and gets stopped as well. But the human head weighs about 17-18 lbs (think bowling ball) and is on top of this wonderfully flexible thing called your neck. Therefore, as it is not restrained by the seat belt, it's still moving forward even after everything else has stopped (decelerated). http://en.wikipedia.org/wiki/Newton's_laws_of_motion So, this bowling ball on top of your flexible neck is still going forward very fast. Your neck muscles are not up to this task being designed and used to just holding 18 pounds or so straight up. Now they're being asked to keep 80 pounds or more of force in check. No can do. So your head flies forward, and then deceleration + airbag exploding at your face around 100 mph comes into play. The rest of your body is strapped into a seat but your head goes whipping forward until good 'ole Newton finally catches up and then is suddenly thrown backwards with great force.

Active headrests are designed to limit that backwards whipping force by moving forward after impact to keep rearward motion of your head to a minimum. Great stuff and highly recommended! If you don't have active headrests, the best thing you can do is make sure your non-active headrest is at the correct height to catch your noggin at the shortest distance traveled going backwards and thereby limit the whiplash.

Sorry for the physics lession - hope I explained above fairly clearly.