The purpose of the car seat trial is to make sure the baby can still breath okay while sitting in the car seat. The car seat positions the baby differently and sometimes preemies have a hard time.
Joshua did great, the test is for an hour, but he was there for 3 or 4 hours with no problems. (He was there so long because they had an issue with the computer to record the test, and then he fell asleep, so they didn't want to move him).
We thought Joshua was getting so big, he seemed like the NICU giant at 6 pounds, and then we put him in his car seat and he looked so tiny.
And here he is just enjoying a meal through the trial.
And just for kicks here is a picture of his sister Minna almost 2 years later when she was getting ready to go home. She is about 5 pounds here and seems much shorter. She also seems to have some bad feelings about getting in the car seat.