Please help: Lightweight infant car seats?

I have permanent muscle weakness in my neck and back after a wreck followed by shoulder surgery several years ago. So I need as light of an infant car seat as possible. I had a Graco with my oldest, and while it was okay, I wasn't necessarily impressed with it. So now for #2 I'm looking at a Maxi Cosi Mico AP. One comment I've seen some people make is that it is a bit long when installed with the base, which is worrisome to me because I drive a smaller car (a 2013 Hyundai Elantra). So here's my questions: