I like the way sims are described in the vid. It is quite true that what is really important is the perception of the car behaviour but in my opinion there is another aspect wich might be even more important: Immersion. It is not enough to have a car the handles or feels "right". If the car handles like a ferrari, but the 3d model is not making you feel you are in a ferrari or even worse, the car sounds like your neighboor's lawn mower, you will never feel the car is "right". That is the difference beetween a graphically impressive GT5 wich lacks that little something to make you smile at each corner and GTR2 or Rfactor which is graphically less good but they are so immersive (I like all 3 of them but they are different).
Now what I have seen and felt playing Speed Dreams, I would say it lacks immersion, graphically and soundwise it is very basic. I don't blame that, I mean some 3d models are impressive (for so little poly) and some sounds are cool and It is not easy to get good sounds and combine everything to reproduce a cars "ambience".
I don't how much the new graphics engine has advanced but I wonder if there is a way to have a higher polycount per car (to make a decent interior), higher texture size and possibility to implement a multi-shader system (that is to avoid a reflective dashboard with leather texture, wich is strange
Soundwise I wonder how much improvements it would make to have a gearbox sound, engine oscilation (after gear change or when reving too low) and more realistic bangs and booms (after throttle release or gear chage), finally a different sound for inside and outside fo the car.
Virtual example http://www.youtube.com/watch?v=1v3StyQONsQ
Real example http://www.youtube.com/watch?v=aDkdg4VMdyE
Speed dreams http://www.youtube.com/watch?v=Z7Fm-daF5Jw
Besides that the physics are quite good in speed dreams. There is only one point to review it is the way a car looses grip, it is totally impossible to drift a car (even in dirt) and when pushing hard the cars have strange ways to slide out of corners, but excpet that I am convinced the physics are good. When experimenting around with setups I noticed it is possible to change massively the behaviour of a car with suspension tweaking and that is a really good point in SD.
I hope this opinion gives you constructive comments and I will try to deliver you some nice 3D models to play with
Have a nice evening.