Sure you can.
We faced our first son rear facing until 18 months.
The second one? Um, 2? Maybe a little later? I don't remember exactly, but the only reason we switched him forward, really, was because we had him in the middle (had to for size of car), and he kept kicking his big brother in the face.
Do a little research on safety, etc.
We have used several different carseats:
1. Diono radian. Nice and narrow but very tall, and very hard to do rear-facing in a small car like ours.
2. Britax - Roundabout, Marathon, Frontier (they get bigger as you go down that list). Britax can be pricey - I tend to buy at Albee baby because they often sell the discontinued and unpreferred colors at a steep discount. And, according to my spouse, Britax seats are FAR superior for ease of installing in and out of the car.
3. Cosco Scenera - this was a seat we bought for our second car, and it was cheap and worked fine. When that car was totaled in an accident, the insurance company paid to replace the carseat. We got a Britax.