I'm almost posi9tive your car has a 12V charger set up for your cell Morgyn. Are you saying it has regular 110/120V plugs like in your house? That would be very unusual. Trust me, you do NOT need an inverter!
By the way, there are two versions of the 4045, on that has 3 places for breakers, one that has 4. You will use the one to the left for you main breaker (maybe 30 amp), the middle one and one to the right 15 amp for 110V and 12V stuff (one for each). If you have 4 breakers, you could use the extra one for a big 110V power load, like a microwave
or AC (or both, just can't run them together usually). I have 4 positions with mine, and have AC and a microwave
, and still have a spare circuit breaker space.
Best of luck to ya!