In California its 4 inchs at the top of windshield (illegal to do the entire thing)
and the driver/passenger are now 70% transmittance (I remember reading they were illegal back in '13 when I last did tints .. Good thing they changed it!)
back windows and rear = Any. (but too dark = hard to drive at night for reversing .. but I guess its okay bc backup cameras)
I honestly have 5% transmittance on my FR-S and its very nice bc nighttime driving most cars behind me have the lights at my eye level. Having my sides at 35% is also nice for the fronts because
side mirror because headlights from behind also shines into there.
It shouldn't be a big problem for the Stinger because its not as low .. but still I think all cars should have tints for a little more privacy and aesthetics .. and the not so really important UV protection but lets add the "health=promoting" marketing pitch for tints ~