Are you driving these on paved roads? I find them to be fairly stable as long as the road is flat surfaced, but take them offroad (the cars at least) and they start jumping around a bit. Probably not too different than real life though, if you exit the road at 100kmh+ on to rocky terrain you're going to have problems 
Beyond that, the major difference between these cars and the ones in most racing game, is that these ones don't have any arcade style controls. In games like those on your ipad, you can crank a turn and the car will usually just perform a perfect drift around a corner - that's not realistic at all, and it takes some extra logic to handle the angles and prevent loss of control. In Outerra if you crank a full stop turn at speed you will likely lose control and spin - just like would happen if you yanked your steering wheel hard on the freeway IRL.
I have thought about writing some sort of stabilizer algorithm to give more of an arcade feel, but it's a fairly involved job. I'm not sure if this is the kind of thing the engine should handle - probably not in the case of Outerra. If anyone wants to contribute some code for this I would be happy to add the option to my vehicles.
All that said, make yourself a nice paved track, get a analog controller, and learn to drive! They can definitely provide a decent driving experience with some practice 
Absolutely beautiful pictures! Now....... what are the driving physics like? Cause' Outerra cars bouncing around like jumping beans is getting really, really old...............
I was driving the Viper yesterday, (one of the fastest and most stable cars so far) and wondering why so many other cars were:
1) Slow
2) SUPER slow on hills
3) Bouncy, bouncy bouncy! 
At a time when a $1 app on my Ipad can give at least a moderatly pleasant driving experience, Outerra has got to be able to handle a mildly believable car after years of trying. Maybe there needs to be a concentrated effort similar to whats happening for airplanes devoted to cars, boats and whatever.
(Climbs off of soapbox)
Meanwhile, Your site is the place to go, for pretty cars, so I'm gonna go grab some more!
Edit: Nice job with the lights! We need more of those! I did try it out on the "Bus terminal" track, and it handles well, also. Unfortunately it bounced, went into some crazy jumping around and eventually got lost beneath the Outerra landscape, forcing a reboot. I wonder if the new collision boxes will help with these sorts of things?
Yup, but I've been driving a long time, and cars don't leap for orbit when you hit a bump, either, arcade or not!!!
Looking at the various vehicle discussions, I think its possible sometimes to get so lost in more sophisticated issues, that the basic stuff that feeds the family gets lost.
Grand Turismo, for instance is not an "arcade" game by any means, and it would run screaming from the current Outerra car handling.
I would say follow the planes, and get a basic car working in a fun way,
then go for the super-realistic simulation quality masterpiece.
There should probably be a well working arcadey vehicle demo script as a guide, that comes with Outerra. The trucks are nice and all, but little Jimmy is going to stay interested a lot longer if he can zoom around a bit, too. The fact is, right now, planes get all the attention by default, because there really
are no other "fun" vehicles to mess with.
We won't even talk about boats.
I've been testing cars on the bus track. It's freaking huge, and works great as a nice racing test area.
