This is one of the very best mods I ever used in this game. It's the closest thing we have to the record cars of the pre-war era, like the Blue Bird and the Railton Mobile Special. I wish someone ventured into creating some like that for this game someday.
But back to the Firehawk, if you're careful enough, you can drive it on thight roads and hillclimb courses, it's definitely way harder to control than a normal car, but mastering the throttle and handling is a matter of practice. Quick launches are hard to keep straight, and if you use it in a timed event the engine will restart itself one of two times at the start line. Dunno if that's a bug or not, but I kinda like it, it adds to the "homemade" nature of this thing. The glorious V12 aviation engine guzzles tons of fuel, but delivers tons of fun in exchange, regardless of what speed you're driving. It's a constant blast, and I hope this mod keeps being updated over time, we can't afford losing something as fun as this. Great stuff.
Let's just start off: this thing is freaking awesome just as a concept. IMO the WWII military looks and 1970s looks work together very well.
Beyond the looks, this thing is a beast, maybe it's not the fastest vehicle (its still frigging fast) and not the easiest to control (once you get the hang of it*, its actually pretty good), but I think you would be hard-pressed to find a vehicle that is as resilient. Not only does it hold together at top speed, but even after significant damage, (including outright ripping off 2/4 front wheels, and bending the frame about 20deg) it can still easily hit 200 km/h, and remain fairly drivable.
I should also note that it's really easy to customize this vehicle too. (For instance, the parts from the Mad Mod actually work with it.)
*(Note: it tends to shoot off to the right for me when flooring it from a stop, but straightens up once you get some speed, I think this is more due to my technique than it is due to the vehicle itself)