I remember having a play with a Citroen AX when I owned the VXR220. It pulled up alongside me, making a hell of a racket, so when the lights changed I nailed it as did he. I had 260bhp in a car weighing around 800kg, so around 325bhp/ton, and expected to leave him for dead.
I didn't.
We came round the roundabout, did the same thing, same result. One more time and this time I backed off as did he, we got level and I gave him a massive thumbs up for having a proper sleeper. No racing, no egos, just a bit of fun between two car nuts. Those old cars (including the Jetta) weigh a fraction of what modern day cars do, so you don't need massive power to keep up in a straight line with modern cars when moving. Zed has a ratio of 190bhp ish, Jetta probably weighs about a ton so only needs 190bhp to match a Zed.
It can happen, but it's rare. The reality is that one person is usually being a bit of a tit, which I guess is where the presumptions come from.