its starting to shape up nicely. What i think you should change is the amount of rubber on the wheels. The reference has almost nu rubber at all, I think that's not practical but if you are going for the concept look than you should mimic that. if you are going for practical style I think you should cut back the amonut of rubber on each wheel and widen the rear tires. To simulate reality anyways i think the rear tires must be wider for this car.
Also I think the wheel wells are too large, probably to accomodate the tire size you've built. But I think they should be scaled down some.

Your proportions also seem to be a little off on the model. For example if you look at the front bumper, the grill above the trim is about the same height as the grill below the trim. This proportion on your model is the same all around the car. I think that you want to have more below the trim than above the trim to get the streamlined look. As right now the whole front end looks a little too bulky.

But I am impressed with the thorough detail and time spent on it, so keep it up and I can't wait to see some more progress.

Cheers,
-Alexander