There really is no way of telling.
First of all, it is an opinion, so there is no way to find out unless you could do a survey of everyone in the world.
You can't base it on the number sold, or the number registered. Cars such as the Lotus, Bughatti or Bentley would rank really low, but they are very well liked and highly desired!
One possible answer might be the Ford Edsel, which was a marketing disaster for Ford when it was introduced and significantly underperformed sales expectations.
However, even the Edsel is popular with some collectors nowadays, if only for its curiosity value.
the least popular girl name in the world is Timber.
EDSEL
Yugo
Vatican City is the least populous country in the world.
bananas are the least expensive and most popular fruit.
the peel p-50 us the least powerful car in the world, it has 4and a half horse power!
£100
Seal clubbing.
sweden
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Seal clubbing.
latican city