The way I see it, the two main benificiaries of traction control will be the high horsepower streamliners/lakesters, and the twin or large turbocharged cars. I believe the former need this feature if for no other reason than to save precious tires. On the turbo cars, it may provide a few less thrills when full boost kicks in, although with the newer computer management systems this may not be as big a deal. With the heavier coupe/sedan bodies, and or the lighter roadsters, I am not convinced that there will be much of a benefit. Most of us are already beyond trouble before we lose traction. 
Hey Bob,
I dont think it will be much help on the turbocharged cars.
The ignition retard method does not reduce the amount of energy in the exhaust stream, it actually increases it. This causes the turbo speed to increase dramatically and the boost to rise right along with it. This is because the exhaust is not expanding in the cylinder, it's doing it in the exhaust just upstream of the turbine.
Fuel cut is really messy as there is almost always a few cylinder events before/after the cut one that the combustion is tweaked and there is popping. This also causes the boost to spike up. It's very hard to tune when it's doing this and under/over correction by the system is the order of the day.
The ignition cut method is the worst of all on a turbo car since the raw fuel is sent into the exhaust stream where it ignites. This method in conjunction with the timing retard is actually used to build boost in drag cars. Exactly the opposite of what you are trying to achieve.
These principles are very clearly demonstrated when at full boost and WOT and you hit a soft rev limiter. The first thing you will see is a nasty boost spike. A soft rev limiter and traction control are typically implemented in a very similar matter.
The auto throttle system is "safe" in the sense that at least it achieves what you are trying to achieve but the boost level will fall off pretty fast so if you have a big turbo then it throws you into lag. An alternate type would put a throttle in front of the turbo allowing the turbo to spin in a vacuum and be ready for work at an instant. This was used by Cosworth and Honda with the indycars in the late 90's. However, it was not used as a TC system. It was only setup to help initial lag when the engine was "breathed" on a superspeedway or a full closed throttle on a road course. In both cases the energy in the exhaust stream was also removed. If it is not then the turbo will dramatically overspeed and when the compressor throttle (vanes or shutter valve) is opened then bad stuff happens!
The selective braking would again be a possibility but in practice I will most always discount it. There is NO commonly available, programmable system like this available. Even if it were, you need brakes comparable to the power you are trying to reduce. On a Taurus with an anemic 4 banger, thats easy. On a real race motor you are talking huge rotors and multi-pistion calipers. It's just not practical.
I see the TC systems finding a niche on medium to high horsepower normally aspirated cars running primarily at El Mirage. I am sure others will try it but I don't see them having much success but I wish them all the best.
A modern boost control system usually sets the target boost level based on your current vehicle speed, gear and/or RPM. It works very, very well (IMO). The best way to control your traction is to not lose it in the first place. That's the type system I use now and will continue to use.
Regards,
John
Poll