deff need more info on your car (yr, mileage, model (base,active,sport)). The insurance company will usually use kbb or edmonds or something of the sort, to determine the value of the car.
Here is a quick search I did on kbb. Keep in mind I used a 98 ti with a few upgraded options.
http://www.kbb.com/used-cars/bmw/3-s...mileage=160000 It may be beneficial on your end for them to use 6 cyl model BMW's as they are probably worth more the the 4 banger...
In our world, we know the value of these cars are worth more than what Kbb says (well most of our cars). But insurance companies don't live in our world.
Good luck and keep us posted