I'm not familiar with the ins and outs of any particular system. I used to do technical and safety inspection for SCCA many years ago, so that's where my tiny bit of general knowledge comes from. Not familiar with using these in 4x4s or street-driven vehicles.
Back when I was doing that, Halon and AFFF were the predominant things. Halon has gone away, I think, due to some kind of environmental regulation or something. I think they have a replacement of some sort for it now, though. Halon was good because it didn't make a huge mess on everything if you had to activate it, but it worked by robbing oxygen from the fire. If it's in the passenger compartment, it can also rob oxygen from the people too, though, so that's a thought. I would guess that the replacement is the same in that regard. AFFF is a foam that smothers the fire with a kinda soapy film. It also makes a huge mess. Might be a bit safer for the occupants, though. I think that if you have to activate your fire suppression system, making a mess is the least of your worries.
If you have a friend in the fire business, might be useful to ask him some of these questions about the plusses and minuses of the different types that are available. I'm just going off of fuzzy memories of doing that stuff years ago. If you have a racing supply shop in your area, they might be able to help with questions about that too, and even provide technical support if you buy your equipment from them.