So Frustrating!

I was at dinner last night with two other couples who also have children. One couple was saying that their almost 2 year old is 36 lbs and that she is a big girl. The other couple who was a 2.5 year old said oh good... now you can put her in her car seat using the seat belt. They have been doing this for their 2.5 year old since she was 35 lbs. I quickly interjected that they can't do that b/c it's unsafe and they said well she's 40 lbs now so it's okay. I had to just leave the topic alone at that point but I'm goiong to tell my other friend that the info is wrong... especially since they have a MA. Why do people who don't know a thing about car seats have to spit out advice for everyone?

them are some big kids. no offense to any one, but they need a health check. my 4 yo is big for his age and was never 40lbs at 2.

Not only is it not safe, chances are it is also illegal. Most states (sorry, I'm not up on the laws) have age 4 as a minimum for CR use and most are going higher (And laws are just that, minimums)

Often "illegal" gets more attention that "not safe."

You can bring up Seat Belt Syndrome and submarining, not to mention how wiggly most toddlers are - does the child REALLY stay seated for the whole trip? What about when she falls asleep? Is the shoulder belt being used? If it's going behind (I can't believe it's not), then you can use the tube of toothpaste illustration for lap belt use only: how the lap belt will hit in the belly and cause internal injury (like a tube a toothpaste being bent in the middle).

Sometimes comfort for the child is a good "sales tool" as well. Even using just a booster, a child would be more comfortable, would have some support when she slept, and would be seated a bit higher so she could see.

I definitely would have argued that one. Since you were having dinner with them (meaning you knew the people at least slightly), I probably would have even suggested a quick trip to the store to purchase and install a seat.