Maybe they just want to admire your cool car. Not every instance of aberrant behavior is a case of someone wanting to race.
I do see more cases of drivers in SUV's or other non-performance cars trying to cut me off than when I'm driving my Caravan. I'm not sure why but I'd venture some guesses. In either car I tend to leave a bit more space between my car and the car in front of me than most drivers do. Not a lot of space, but more than the not-enough most drivers allow. The Cayman being smaller, drivers following me can see around or over me to know that space is there. Or they just think I'm an obnoxious Porsche driver and need being put down. Whatever.
That is a good point and sometimes it is just people admiring a nice car. I have to admit I do that too but there is a difference in behavior and I think its obvious when the other car is trying to bait you into a race. By pacing at exactly the same spot in the adjacent lane the perspective of what they see does not change so I think its just bait. BTW, I usually respond to these drivers by very slowly slowing down. At some point, typically, they get frustrated I suppose because they are now going too slow and I am not taking their bait, and suddenly accelerate. For cars following too close, I keep slowing down 1 mph by 1mph. At some point they just get pissed and accelerate way ahead of me and the annoying pest is out of my life.
A couple of months ago while driving my Z4 with the top down, I passed what appeared to be a fully restored teardrop headlights 1952 Buick convertible on I95. The car was beautiful and that model/year has a lot of nostalgia value to me because my dad had one (not a convertible) and, being the first car with an automatic transmission, I have clear memories of sitting in the back seat as he took friends and family for rides to show them how a car without a clutch and gear shift drove. I slowly passed him on the left, slowed down, changed two lanes to the right, and then slowly passed him again on the right. All the time we giving each other thumbs up. I am not sure if the driver enjoyed the attention more or I enjoyed the nostalgia trip more. That's what checking out a really cool car is.