Not sure about your actual question as regards exhaust and ccsvi...but I felt I just had to respond because of the toxic element to car exhaust, which will affect the central nervous system, which in turn will affect MS. There is much evidence to support the inhalation of toxic fumes and its negative impact on the central nervous system.
I am a painter and last year while working with oil paint I got a little too close to the turpentine I was using, sort of had temporary amnesia (which can happen when doing something you love) over the toxicity of turpentine, or paint thinner, and it's affect on the central nervous system...I had a major relapse this last year and I am almost sure it was due to this toxic overload. Our house is totally free of toxic house products, like cleaners, etc. There are a lot of natural alternative that can be used for cleaning.
However, I am not sure what to suggest for your situation, except that if you feel your symptoms got worse in that environment, then I would suggest getting out of that environment.
Any way to get in another department away from the exhaust? or to use your skills while not around the exhaust? Sorry if this is a stupid question, I don 't know about car stuff....(but I can answer questions about art!!)
Good luck, and I hope this is helpful in some way,