The Eon however is the better overall car. It offers first in segment features, better ride quality and style. The car has definitely changed the way one looks at affordable cars today and it's the Hyundai that wins today's fight. :)
If you are experiencing too much smoke from the exhaust of your BMW 3 Series 320d Luxury Line, then you should take the vehicle immediately to the authorized BMW service center as it could be a throttle body issue (meaning it needs to be cleaned) or an issue with the engine head as a whole.
BMW 320D Sport and Luxury Line, both come with sun roof. To know about other features of the cars, please visit to the below links-
We are offering the best comparison between Audi A4 and BMW 3series.(diesel variants). It will help to choose the best one car in your affordable budget.