I know its been a month but I felt I had to weigh in on this topic, and seeing as we are just speaking about how it would work and not "ADD TO GAME PLZ" then I feel that this could be fun to speculate... so lets begin!
Tank Tracks... Synonymous with strength and power in vehicular form, it almost seems like a match made in heaven for the cars in GRIP. Now yes, there are a few flaws as you have all pointed out: Speed, weight, complexity, and a slew of other problems that would make them a downright pain for these cars... so lets try to tackle them and justify the insane shall we?
I'm gonna start with complexity. While they are extreamly complicated, GRIP takes place in the far off future where hauling these cars from planet to planet is apparently no problem, so in terms of complexity and the breaking all the time, I am going to take the cheap but totally logical way out of this problem and say that technology has advanced to a point where highly complex systems (such as this) can be built with a reliability that is just completely unrivaled by todays technology. Solved... all be it in a cheaty way, I know... but still... moving on.
Weight will be next on my list... and weirdly... I am going to say something sort of insane, but I want you to hear me out. I am proposing that this far into the future, they would actually be able to create a set of tracks such as these that would be LIGHTER then the behemoth wheels that are being used! Yea! I think it would be totally possible!
The wheels that are used on the GRIP cars are nothing short of being practically indestructible (or can they be destroyed? I didn't think they could be but I could be wrong) with being able to shred over nearly any terrain at 500+kph, slamming into the ground, rocks, and other cars like they arn't even there, getting shot and exploded by missiles like its no big deal, all while catering to the insane levels of cornering grip and G forces that these machines can generate. These tires are tough. To counter all that heavy abuse means that the tire would have to be a thick build up of interwoven rubber (for grip and dampening forces), carbon nano tubes (for added strength... more future stuff), interwoven carbon fiber/graphene sidewalls, and probably some layered graphene to hold it all together. I am also going to go out on a limb here and say that the rubber contained in the tire is not a solid, but a liquid. A liquid that once exposed to air would form a strong shell of rubber (basically a futuristic version of green slime built right into the tire). This mixed with carbon nano tubes would form a really good seal if the outer layer of the tire were ever punctured. This would make the tires nearly burst proof. Not only that but it would make the tires rather heavy even though it is using all these innovative and light weight materials, and what is bad for speed? Weight... especially in the tires.
Assuming that the tires could hold up to the insane centrifugal forces, we are going to need an insanely strong rim to be able to deal with all of the forces that are being generated by the tire. My proposal? A 3D printed graphene and titanium lattice structure that is designed to reduce the weight and be as strong as physically possible. I can't really envision a real way to hold up to these insane forces so I am just going to wave my wand and say "future stuff" again but this is my best guess as of now.
So yes, even at their absolute lightest, these tires are still going to be insanely heavy to deal with all the insane forces that are at play here. So now the question becomes as to how on earth we can make Tracks that are LIGHTER then these tires? I mean, in all honesty, it does sound a little insane... but I have a few ideas.
The first thing that comes to mind is don't mess with a good thing. The GRIP cars already are fairly stable at insane speeds with their tires on all four corners of the vehicle, so we arn't going to change that setup. We are going to leave that completely alone and replace each tire with its own independent track like Mattracks. That practically solves all the controllability issues and the need for a new driving and control mechanic right there.
Now that each track has been reduced to the size of a regular tire we have saved a lot of weight over a traditional track vehicle design anyways. But lets keep going. In a tracked system, the track is the only part that actually comes into contact with the ground and makes the full loop of the system to then be exposed to the centrifugal force. The rest of the system is just small cogs and roller wheels that you would be able to spin at insanely high speeds before ever blowing them apart from the centrifugal forces that would be created, especially with the technology that we just used to create the wheel rims up above. Knowing that the track is the only part of the new propulsion system that is going to be feeling the full effect of the centrifugal force we can just take the track and design that for maximum strength to hold up under the insane speeds and centripetal force that is trying to pull the track links apart. I also feel that building the tracks out of metal and just using rubber pads for grip is the only sane way to go if you want it to hold up to missiles... granted we did just make a tire that can do that... ehh... metal tracks are cooler... plus I am going to use that in a minute.
Making this thing even lighter, since we don't have a rotating rim, the core support system of the tracks (look at a Mattrack to see what I am talking about) can be made far lighter then the rim of the large wheel we made while using the same technology. It could be built so much lighter just from the fact that it wouldn't have to deal with the centrifugal forces being created by driving at 500+kph that we would end up saving the bulk of the systems weight right there. But what about all the insane landings and bumps in the road? Well, Mattracks have their own integrated suspension system built into each track. This would mean that between the suspension system of the tracks and the suspension system of the car (crazy magnetic forcefields for the win) that the design would be under far less stress then a normal tracked system (like on a tank) even. This means that we would be able to take out even MORE material from the support which makes it even lighter!
And yes, I am proposing that with the future of tech and building metal lattice structures... it would actually be possible to make a track system even lighter then a wheeled system... but there are a few more problems we have to tackle.
Biggest of all (and truly the make or break moment here) is speed. Speed, speed speed. What would be the point of this upgrade if we couldn't keep up with everyone else right? That would be literally pointless.
Now its time to really pull the magic out and go full future nutcase here... with a commercial from 2014... watch till the very end.https://www.youtube.com/watch?v=6zTxMwYM1tI
That right there is the answer to our speed problem! If we were to keep the tracks in their original shape, at each sharp change in direction on the system, the centrifugal forces would be SO INSAINLY HIGH that the tracks would just instantly explode. So I propose a transformable track... one that at low speeds (in these cars cases probably anything under 200kph) you would have a track shape giving a huge footprint and insane levels of grip that would keep the cars under control seeing as they can be a little squirly at low speeds (Ah rollcage... great to race... impossible to recover once you wrecked... many a spinout at under 100kph). This also could be used for dampening the huge forces off a landing from a jump. Since the system is dynamic, it could form the shape of whatever it slammed into... again giving a huge surface area and loads of grip... no more loosing control on landings again! This system could also be easily designed to be deployable in either direction... you know... to compensate for the fact that the cars can flip onto either side and keep going like noting happened.
Once a higher speed is attained however, the track would form into a wheel (basically) allowing a reduction of centrifugal forces and a huge boost in the potential for speeds that the system would be able to hit now. This system would then (in theory) not only be able to hit the same speeds as a wheeled vehicle... but oddly enough... with only the track having centrifugal force on it and being made out of metal rather then rubber (yes I know there are nanotubes in it but I still don't think its as good as good old fashioned metal construction)... even higher speeds without breaking then the regular wheel would seeing as their is far less spinning mass to create those forces. Yeah... thats right... tank tracks FASTER then a wheeled vehicle... now this sounds like fun!
Now the Mattracks system uses a couple of hydraulic cylinders and what looks to be an inflatable inner-tube. Now thats all fine and good with the hydraulics, but that inner-tube... we are gonna need something a little more... insane... to deal with the craziness of these machines. Instead of an inner-tube I say that we should use a central hub that uses magnets to not only repel the track into the round shape (probably wouldn't even need it for that with all the insane centrifugal forces going on) but to hold the tracks in place and keep them from derailing off of the system... kinda like how a maglev train works but from a much longer distance.
Now to hold the tracks in place around a corner, the magnets would have to be ridiculously powerful so just like the way that the tires are held on, these magnetic fields would probably also warp the light going through them creating the trippiest wheels you have ever seen!
This is just my vision on the topic... if I get creative I might even drop a design drawing on here of a proof of concept because the more I am writing this... the more I want it in the game
Anyways, this is just my look on the subject... what do you guys think about it?