So it should be a 1949 roadster based on a BMW 315 (or 315/1).
Bodied in 1948 actually but we won't split hairs..
I think the basis must be a 315 as it's described as a one and a half litre car.
Below is the advert; I must admit when I found this I thought it was built by a coachbuilder called Deze, who of course I'd never heard of. Nor could I find any mention whatsoever of such a company; then I realised it only means 'This' in Dutch! So that didn't leave a great deal of information but I thought no matter, Wendax will know exactly what it is!
Maybe it was built in Holland, though it's odd that a coachbuilder is not mentioned in the advert.