The starburst is a little too distracting and I reckon it could do with toning down a bit, perhaps try f/5.6 and see how that looks. Also at these long shutter speeds you are either going to need a flash dedicated for lighting up your dog so that the shutter speed will only effect the ambient or you will need to blend multiple exposures. The former will be easier and it would be even better if you had another flash behind your dog for some edge separation.
If you can't get a second flash then you could try experimenting with daytime shots playing with depth of field and throw the police car slightly out of focus to draw the attention firmly with your dog. I don't know your equipment but a couple of ways of doing it:
1. Very wide aperture. Like this but at night:
http://blog.markrogersphotography.c...man-shepherd-police-dog-k9-and-police-car.jpg
2. Using a much longer focal length, but you'll have to be much further away for taking the shot so if your dog takes a disliking to a passing chav then it could be carnage.
3. Moving your dog further towards you and away from the car, not sure how the perspective will work and the car may end up lost behind your dog. Perhaps something like this:
http://blog.markrogersphotography.c...r-german-shepherd-police-dog-k9-squad-car.jpg
I think I can envisage what you are trying to get but I think daytime will probably make things a lot easier as to make a night time shot look really good, as in pop, I think you are going to need multiple flash units for both your dog and the car. It may be worth having this thread moving in the lighting section as there's some guys in there who know a shed load more about flash than me!