You managed to capture the shape pretty accurately. I think you could avoid the gap in the rear by building the whole rear section on a 3 x 4 surface and mounting the whole thing (SNOT) on the back. Furthermore, the side of the car is pretty well proportioned, but I feel it's too narrow for it's length/too long for its width. And whereas the width is approximate minifig scale, the length isn't (although it's hard to define minifig scale, so it might be a matter of preference, but it's definitely too big to fit into the current City line). For minifig scale, I think the wheels are too large and personally I don't think those wheel arches really fit with such a small car.