I still drive my Trojan around Central London and it generally keeps up pretty well with the flow. However, because so many motorists ignore all laws and rules of the road, and drive at whatever speed they think they have a "right" to, Speed Limits are now completely disregarded. So speed humps are being put on more and more roads, and some of these are pretty savage to anyone in a mini or micr car. In fact it is only huge wide Executive cars and 4WD which can really deal with speed humps comfortably, so increasing numbers of drivers feel justified in up-scaling their car, and the manufacturers are only too happy to oblige.
Back in the days of Minis, Bubble Cars, Austin A 30s, Morris Minors etc 60 mph was more-or-less top speed, and the lack of seat belts, Anti-Lock Brakes, Air Bags, Impact Absorbing zones, modest roadholding and acceleration people were not able to drive like maniacs down crowded urban streets, and did not feel safe when going flat out, especially as the steering started getting light and vague!
I have long felt that a return to light, compact and simple cars with much more modest levels of power and dynamic ability is LONG overdue.