Also, how would you convince your child to stay in a belt-positioning booster when your state's law does not require anything other than a seatbelt after the child reaches 4 years of age? She has older friends who sometimes only use a seatbelt.

Since child seats change like women's fashions, it's hard to say what specific seats you should be considering. On a more general note, since she seems to be concerned about how other kids ride, I'd suggest finding a seat that makes it easy to buckle and unbuckle herself; Something that looks like a grown up seat and less like a baby seat. That way she has some control over the situation as well as more autonomy than in her baby seat. Plus, if you have a friend in the car she won't be embarrassed. Obviously, you need to find a seat that fits her frame and is comfortable to sit in! How it fits in your car is also important. My 5-year-old son is using a Graco Turbo Booster high back seat, which I love for a couple of reasons. Most importantly, the opening for the seat belt is big and allows the seat belt to extend and retract normally which makes buckling and unbuckling much easier than seats that hold the seatbelt tightly. He likes that the seat is "cool" and has armrests and cup holders. That company makes a backless version as well that uses an adjustable tether strap and guide to hold the seatbelt at the proper height. It looks more like a cushion than a big car seat but still keeps the seat belt positioned correctly.

Keeping her in the seat is another matter. At 4, it's still a bit hard for kids to understand the whole array of safety issues and how badly they could be hurt if they aren't strapped in properly but being buckled still needs to be a firm rule. Explain as much as your child is ready to hear. Don't scare her with horror stories about car accidents and dying toddlers, but do explain that sometimes cars bump into each other or mommy has to stop quickly and that can make kids slip off the seat. Also highlight the benefits of the seat like sitting up higher and seeing out the windows, having a cup holder for drinks and snacks, or having a special place to rest their head if they get tired. In the end, kiddo needs to know that use of the seat is mandatory until they are big enough to use the regular seat. My older kids had to be able to sit up straight in the seat and have their knees bent at the front of the seat without slouching or scooting their butt forward. That was the price of admission to the 'no more booster seat' club! My kids are pretty tall so in Auntie's car and Grandma's car, where the seats were smaller, they were allowed to ride without the booster when they were around 5. The seats in my van are much bigger and deeper so they had to use the boosters there longer. Make a rule that the car doesn't go until kiddo is seated and buckled. Make another rule that unbuckling or turning around, lying down, etc will cause the car to be pulled over until she's back in the right position. Stick to it, even thought it IS a horrible pain to have to pull over mid trip! Eventually, she'll come to realize that it's no fun being late for things and it's really boring sitting on the roadside doing nothing. If she argues that Sally doesn't use a booster seat, point out that Sally would if she were your child! If you have a problem with her unbuckling the latch while you're driving, you can buy a special cover that goes over the release button that needs 2 hands to open. If she's really unwilling to sit properly in the booster then you may want to consider buying a new toddler car seat that is rated to a higher weight, whether she likes it or not! Britax makes several models, even one that goes up to 105 pounds! And while it seems silly to pay several hundred dollars for another car seat that she will outgrow in a short while, if it keeps her safe for that time it's worth every penny! I've said before that I will happily listen to my kids yell in indignation, strapped snugly in their car seats than hear them cry in pain in a hospital room, or heaven forbid not cry at all in a funeral home.