Originally Posted by
hillrider
Car seats secured with LATCH system (bottom two anchors, not the top tether) perform much worse than the same seats secured with seat belts (various sources, including Consumer Reports). If you have an IQ high enough to follow directions to attach a car seat using seat belts (and apparently many people don't, hence the existence of LATCH), you should only use seat belts and can lighten your seat by simply cutting off the separate LATCH anchors/strap.
It depends entirely on the car and the seat. We have two Britax, one for each car. In my car, it fits very tightly and securely using the seatbelts. But in my wife's car it is horribly loose and ill-fitting when installed with the seat belts. We always have our car seats inspected by the local county sherriff's office. Their professional opinion is that it is better to use LATCH if it makes the seat fit more securely.