Usually when we say the car is an 'Uncle Car' it means that the car is super dull looking. Something like a two generations ago Toyota Camry or the A33 Nissan Cefiro. These are super boring to look at cars and usually driven by slightly elderly people who are as super dull looking as the car. However, sometimes even a somewhat interesting car like this E46 BMW 318i gets called an uncle car by the people trying to flog it off.
