I came across this cool video of the gerolsteiner team motorpacing: http://www.dailymotion.com/video/x5f2sv_entrainement-sprint-gerolsteiner_sport?from=rss

Motorpacing allows riders to simulate race speeds and above.    If you watch the video, you'll see that the riders draft behind the car, and then sprint past. This creates a situation that is  similar to the what they might encounter  at the end of the race, and is almost impossible to simulate without the motorpace.   Motorpacing also simulates the momentum that you feel while zooming along with the pack....pretty hard  for the Gerlosteiner guys to do unless they can find 50 other pro riders to break the weind for them during their training session.

    I motorpace riders at the track all of the time, and it benefits both track riders  and road riders alike.  Pacing on the track with a motorcycling is much safer than what these guys are doing...behind a car on an open road.... I definitely wouldn't recommend it.  But then again...it might be safer than some of the group rides I've done!