If you go to youtube and search "5 point harness car seat" you will see a story about why the 5 point harness is the best way to go for as long as possible. Don't be fooled by the other car seats that say "up to 80 lbs" etc - if you look closely they all say "up to 40 lbs as 5 point car seat, then 80lbs as a belt positioning booster seat". It's a heart breaking story - and I can't stand it when I see people recommending "cheap inexpensive $30 booster seat" etc. My daughter is 5 and is just over 40lbs, but tall for her age. If I had seen the video on youtube, I would not have gotten the Eddie Bauer seat that we've had for the last 4 years. I love the seat, and my daughter found it to be comfortable and we are in the car alot and travel frequently so she spends alot of time in it. Recently - while on our way to Orlando - I was reading the Sunday paper and ads and almost fell out of the car while my husband was driving. We've been wanting the Britax seat and had been kind of looking for it for awhile, knowing that she was on her way out of the other seat. The TARGET ad from week before last - had the BRITAX REGENT on SALE from $279. down to $179!!!!!!!! We raced to the nearest Target store, and couldn't find the seat. The employee then pointed out to me that it was an "online sale" only. I got online at home as fast as I could and ordered it right away. I was a little bummed that I was going to have to pay shipping, but thought "what the heck" - "we're saving $100. on it!". Well, Guess what? TARGET is/was having a special - FREE SHIPPING ON ORDERS OVER $50!!!! I ordered that seat as fast as I could. The Marathon is on sale also - but not as big of savings. The seat came in about 5 days, and it is WONDERFUL. It is very large, and the 5 point harness is very adjustable. It says that the material is already stain protected, but I sprayed it with Scotch Guard anyway - as I always did that with her other seats, and they launder beautifully, wash, put back on and air dry, spray again.
Anyway, the Britax Regent is in our car now. Thankfully, I only have 1 child, and an SUV - so I have it installed in the center position of the back seat, and it is fine. It will fit in one of the side seats if I ever need to put in another car seat, but then the center will be very tight if another person were to need to squeeze in. My daughter says the seat is very comfortable, and as I mentioned, she is very tall - and still has one more adjustment on the shoulder straps to go up. If you do order it, one tip - the owner's manual/ instruction sheet, is fastened under the seat cover under where the child's left leg would hang down the front of the seat. I called the # because I couldn't find it in the box, and was convinced that it had been left out or something.
My husband is a retired law enforcement officer (back injury), and a performance driving instructor / race car driver / race car builder. He has seen first hand the forces that a human body can incur during an accident - and our daughter will be in that 5 point car seat system until she is at least 80 lbs. My sister's kids were all adopted from China - and they are all on the small side, she jokes with her 9 year old, that at this rate Olivia will be taking her driver's license test in a 5 point car seat!
Good luck!