It is not just possible, it's just what I recommend. And yes,
all the ferries I have mentioned admit vehicles. During winters, when route 63 is closed, the ferry is the only contact the residents in Geiranger have with the rest of Norway. Would be too bad if they wanted to go to the nearest "city" (Ålesund) and couldn't take their car with them on the ferry ...
Cost: If you decide to go all the way to Åndalsnes, that means a total driving distance of approx. 420 km each way. That means 840 km in total, and if you rent a small car (ilke a Ford Focus) you'll probably use about 0.7 liter per 10 km - meaning 60 liters in total, which would cost you about 750-800 NOK. Say 1000 for a conservative estimate.
The prices for the four ferries involved on the entire route from Bergen to Åndalsnes (car shorter than 6 meters, 2 adults including the driver - all of these are one way fees):
Lavik - Oppedal 130 NOK
Anda - Lote 83 NOK
Hellesylt-Geiranger 411 NOK
Eidsdal-Linge 81 NOK
The two ferries in the middle can be avoided if you instead take this route:
http://kart.gulesider.no/m/pRmM2
This means you take off from E39 earlier, and you get another route down to Geiranger. A little more driving, but much of it is through nice landscapes - and if you think economy you'll probably save some money this way.
Or of course you can take the ferry on the way north, and the road on your way south.