Is this safe?

JL

We had one of these suits (pictured below) for our son to wear in his car seat during the winter...however he was about six months old when we were using it, so he wasn’t so tiny. They aren’t very bulky, I’m sure a lot of you are familiar with them. We bought a new one for our baby that’s due in a few weeks. Would it be unsafe to put them in it for the drive home from the hospital? I’m just picturing them being so little in the car seat I’m worried it might be too much bulk when they’re so small. I’m starting to think I should just use warm blankets and wait a couple weeks to use it?