Will a Britax Roundabout 55 fit in my 2009 Honda Fit?

Short answer: Yes!

Now for a brief review of the Britax Roundabout 55.

After wrestling & fighting with our current convertible child restraint (an Alpha Omega Elite I bought in 2009) and scraping up my hands every time to install it with the vehicle seat belt (the LATCH anchors no longer maintained tension), I broke down and decided we need a new car seat for my daughter. If it can't be installed properly, don't use it.

I looked at reviews online (mainly on Amazon) and took advice from friends. I narrowed it down to these three: Graco MyRide 65, Chicco NextFit, or Britax Roundabout 55. I ended up picking the Roundabout, because there wasn't anything in the consumer reviews about it not fitting in a smaller vehicle. Even though we're thinking about getting a bigger car, I wanted to be absolutely certain I would have no trouble at all getting this in our current car or in a friend's car when we travel. Other key factors were: desired to keep my 2 yr old rear-facing, brand trustworthiness, price, styling, height/weight fit, ease-of-installation, and type of anchor mechanism.

The Britax arrived in the mail today, and installation was a breeze compared to our old Alpha Omega. I'm very satisfied. My daughter couldn't wait to get in and try it out. With the Roundabout rear-facing, I can actually move the front seat aaaaall the way back without interfering with the child restraint! Before, we had to move it up so there was only just enough room for an adult to sit up front.

 The LATCH anchor mechanisms are the type with a button up top, so I don't have to dig to depress the anchor.

 

See that metal bar under the shell of the seat? 

This seat has a bar upon which the LATCH tethers simply slide up/down, 

so when it's time to switch to forward-facing, I won't have to re-thread the belt path.

  

 Here it is: all installed in our '09 Honda Fit! It will work great, even  with my 6' 2" husband in the front seat. I hope this seat works out for us, because it's SO much easier to use!
(P.S. It comes in different colors, too!
P.P.S. Made in the USA!)

Why is facing rearward so important?

Wow. I found this great answer to that question on carseat.org...

"Babies have heavy heads and fragile necks. The neck bones are soft, and the ligaments are stretchy. If the baby is facing forward in a frontal crash (the most common and most severe type of crash), the body is held back by the straps, but the head is not. The head is thrust forward, stretching the neck. Older children and adults wearing safety belts may end up with temporary neck injuries. But a baby's neck bones are soft and actually separate during a crash, and the spinal cord can tear. It's like yanking an electrical plug out of a socket by the cord and breaking the wires."