With all the testing going on at Jerez for the F1's at the moment, I downloaded the beta track by Prblanco and Laguna - WOW!
The layout and track elevations are great to run on. Ran about 20 laps there just now.
Just wish that maybe someone could finish off the track with a few more trackside details? That would make this already great track a truly great GP4 track! Having said that, and with no previous knowledge of using GPBuilder, I might take a look at adding some simple things like braking markers....!!