I am a huge advocate of car seat safety - proper usage and keeping children in car seats in the proper position for the proper length of time. Following your manual precisely is very important when installing a car seat and, if possible, you should have your seat installation inspected by a certified car seat technician. Parents also need to be cognizant to never use a car seat with unknown history (i.e. never buy a used car seat from a stranger) and also be aware that car seats do expire (generally 5-6 years from the manufactured date - located on a sticker on your car seat).
The reason I bring up the topic of car seats is because I was helping my co-worker research which infant car seat would fit best in his wife's Mini Cooper (they're expecting their first daughter in November). I am a member of the Car Seats for the Littles Facebook group and I found this awesome comparison they did of infant car seats in compact vehicles. I wanted to share in case any one else out there was facing the dilemma of what car seat to get. It's a comparison of 11 infant seats all installed in the same vehicle with pictures for comparison purposes. You can see the article here.
If car seat safety is important to you (or you regularly share information with other mothers and would like to be as up-to-date as possible) I highly suggest you join the Car Seats for the Littles Facebook group.
Lastly, if your seat is expired, too small or used (has unknown history) you can trade your old car seats (and other baby gear) in for 25% off a new one once a year at Babies R Us (generally in the Jan-Feb time frame).