man, that image is ALL chopped up.
you can see the poor masking job around her hair, arms and the rear window. better viewed in really small resolution.
anyway - you've got a 5D2, right? set that sucker to ISO 1600, put your iPhone (you have an iPhone, right?) in the Flashlight app on full brightness somewhere in the dash display to the left - this will be your model's key light for his/her face. if it's too low, set it up so it lights the face in a way that you're happy with. put your camera on a tripod outside the glass to take three or four shots - don't move the camera, obviously until all your shots are taken.
get some green material to drape over the outside rear window and hit it with your flash from the outside. if you don't have a wireless trigger - set it up for a 2 second delayed exposure and run back there and fire the flash manually. (your model needs to stay as still as possible). this green frame will be keyed out later in photoshop. for the street scene, just take an out of focus frame of your choosing. using this chroma key method will prevent that harsh mask look that this photo has - and it'll look more real/natural.
for the windscreen light reflections, as stated above, string some lights over the car - these should be visible when you take the shot of the model.
for a kicker, get a wired PC sync that runs from your camera's hotshoe to your flash and set the flash up in the backseat so that it'll highlight the model's rear side and the back of the front seats. this will be light coming from the street outside the rear of the car.
for the long exposures, you're going to need to test out an exposure that works so that the highlights are not too much brighter than your model's face. trial and error here unless you've done this before.
there are many ways to do this type of shot - this is just one. there are easier ways, but you'd need to get some gear that you probably don't have. the method i've described here will have a more natural feel to it - not like someone took a studio strobe and set it up in front of the model's face just outside of the car.