I believe there's a whole set of behaviours and unwritten protocols around how close people drive to you.
When I used to drive my old E30 325i (which was quite a fast car for its time) I never really had any bother with people getting too close behind. On the other hand, anytime I borrowed my wife (then girlfriends) little Fiat Uno - the fkrs were always all over my back bumper. Same speeds, same driving style on my part, but it was as if the Uno was an affront to their virility: track position/ being in front and not stuck behind a poxy little shopping trolley of a car became all important to them - especially the thrusty aggressive executive types in their Audis and BMWs.
The most interesting one of all was how people reacted to my Exige - confirmed by a friend of mine who also had one. Driving along any road, the first thing that happened when a car appeared behind was it would more often than not close right up to your chuff to get a close look, check it out (read the badge perhaps) and then, invariably back off to a more respectful distance. They definitely seemed to afford you a measure of respect you wouldn't have got in an Uno 45.
The other interesting thing was no matter how much you slowed down, or how big a gap you left between yourself and the cars ahead when you were in the Exige - hardly anybody
ever ventured to overtake. It was as if they seemed to take the view - well if that's all the speed he's prepared to risk, I'm not going to be daft enough to try to go harder, or maybe just a case of not having him think I'm having a go
Man I miss that car at times..