I'd think not, because unless it was his, or something related to him, to remind people of him, I'd highly discourage it. If you have to even ask, then its probably a good indication that its not a good idea. Even though some might think it is ok, still dont account for the people who might think its not ok, and if it upsets some of those people who dont agree with it, who are also in the procession with you, isnt that just adding more to an unpleasant event for them? They sure dont need someone else to funnel that too, aka the guy who drove a flashy sports car to a somber event.
Again, special ricumstance, like if it was a long standing viper member, huge car buff and what not, and a bunch of his friends/family drove sports cars as a tribute to him, I would think it would be a great show and dedication to his life and his love...
But I dont think this situation justifies.
Definetly not looking to offend anyone, simply my opinion on the matter.
Jon