do you have the model for the car, too? because gta4 files are always locked, so we can't access the model in it. i already had that problem, the author agreed that we can modify the car, but he didn't have the model file, only the gta4 wft file, and since it was locked, i couldn't use it.
That particular car, was not locked and I was able to import it using zmodeler 2 and then export it to 3ds format.
I am sorry I haven't replied, but I have been SWAMPED :-)
I will try to find time to send you the car as soon as I can in case you haven't already downlaoded the car, right now it is STILL just sitting on my harddrive... the car does however need to be modified/prepared in zmodeler or a similar program.
I downloaded the car from here...
http://www.gtainside.com/en/download.php?do=video&did=27844&cat=456&start=0&orderBy=&vid=1The car can be imported in zmodeler 1 or 2 and exported as a 3ds model, since it is not locked.
The car has a completely modelled engine and engine bay.
I also have some unreleased cars from Mr Chris on an old harddrive somewhere.
Perhaps CJJ can find some time to help with this. I will also devote some time to SR3 again as soon as I gain some freetime again at some point.
also, there are a lot of models out there that were just ripped/remodeled from other games, or stolen from other modelers. that's very common in the GTA community (that's why most of the scratch modelers left the community 4-5 years ago).
i know the Mercury Monterey is not one of those, Driver was a modeler in the GCU community, he modeled that car. if you have the model, please send it to me, and i'll use it in unity.
about the engine: you don't have to experiment with anything else than Unity, in fact, you don't have to experiment with anything, as i'm doing all the work in the engine. if you want to help, then try and get more models from the guys out there, as it's a very time consuming task, and i don't have the time for that.
The experiments we did in irrlicht was because there was no indication that anyone else was devoting coding time to the project, so we decided to try some stuff out in irrlicht

I have also been looking into unity, but I haven't been able to find time to do any kind of significant work in it. Looks like a good game engine though :-)
Also, I think it is impressive what you have accomplished in unity so far :-)