Every 4 years it seems there is a model or brand that is cool, and that every elite seems to be driving. Is that the cool new car? The "in" brand. No. The cause is simple. Its 101 economics:
Import duties are usually managed on a country-by-country basis. Politicians will manage capital flight ("trade imbalance") by seeking higher levies on heavy industrial goods that are popular, like cars. Those levies lead to a situation where everyone seems to be driving the exact same brand new cars (and usually 1 particular make). However, its not that the brand is particularly popular, its only that the car maker offers the best value net of import duties, plus, importers are very wary of bringing cars with huge import fees.
So, the newer cars are always a few specific never-seen brands or makes. Then there are others driving slightly-older Y brand cars, far more generic. The oldest cars seem to have a lot of diversity and would resemble your average US used car sales lot.
The evolution of the duties can then be described as follows: 1) free market: very low cost to import any car 2) Some tough -but not insane- duties (particularly on US new cars). 3) Restriction / heavy levies on used car imports. 3) Very heavy import duties on most western new cars (vs Indian or Chinese makes).