@Krzeszny As I have stated several times in various places... Source does not allow for a vehicle with high torque to go up a hill but lower top speeds when on flat ground without just slamming into what feels like a very hard set limit. So if you would like, you're welcome to try to do it yourself with the scripts TDM provides on his SVN, or write from scratch and see if you come up with something better. As to your point about it being only two wheel drive, that's actually BS considering I can tell you right here and now that it is simply untrue, it may seem that way when the wheels are punctured but that is how it must be done as to create a realistic sense that the vehicle has little grip with rims alone. Again if you'd like to do better, have at it, I'd like to see what you come up with instead of simply complaining.
I am very tempted to list all vehicles, with prices of purchase and per upgrade and allow people to try to figure out a better system of balancing than what I presently have in place. Adjusting the current prices is out of the question as people may already own that vehicle which would either give them a bad deal or an extreme boost/easy money. I'd be curious to know how people would rather do it. All I can tell anyone attempting to do it, beyond 120-140 the vehicle handling starts to become a bit sketchy and acceleration required is extreme at the slightest touch, so I would recommend you stay below that.
Additionally, it must be noted that we deal with a rather inflated price over the real car as there's multiple expenses that you do not have in the real world of cars so even if a real Nissan GT-R isn't a huge amount more than a BMW M5 or similar, the price you pay in the long run is much greater but not on the server. So that's one reason prices are as high as they are, as well as the fact that coming by money isn't exactly a hard task, so you'd afford a GT-R or any car for that matter in a couple days so cars that should feel "rare" and "exotic" are just commonplace and no standard cars are driven making those entirely pointless to keep around.
In summary, my feeling is that the more you pay for your car the better it should perform, so if you put a 150k improvement into a 300k car it should be roughly the same as a 450k car base. So that's what I have balanced for the most part to be like without having to change any price of a car to make it fit this. There may be a few cars that "should" perform better than they do but I could find no way to properly balance this with the problems I mentioned before about higher speeds. All I can say is this, if you feel like you have a better scheme, feel free to suggest how you think it should be done because realism is not fully compatible with Source engine as well as the existing structure we already had.
P.S. Anyone that had the fuel bug over the weekend you should've found your car to have nearly a quarter tank of fuel so you could easily go get it refilled. If Garry's Mod updates were more reliable, this wouldn't have happened...