Before buying
anything, I'd see what the car seat (child restraint seats) capabilities of the vehicle would be; after all, its a family car. Do you need to fit 3 car seats across? Are they all rear facing or forward facing? Are any in backless boosters (which usually take up less room)? Are there upper tethers for all 3 seating locations? Is there LATCH (upper and lower anchors) in the middle seat (99% of cars do NOT have lower anchors in the middle and you CANNOT 'borrow' an anchor from other side seat). Btw, the Impala is one of very few cars that HAS the LATCH system in all 3 seating positions.
I happen to prefer seat belt installs for any car seats I help install and will go to LATCH's lower anchors when necessary to tighten a loose seat, but they're not superior to seat belts (common misconception). The upper anchors (those hooks you see along the back windshield or in the cargo area of your hatchback or SUV) MUST be used for forward facing seats and some/all harnessed boosters. It keeps kids' heads from flying forward up to an extra 6 inches (which could mean a matter of serious, bone-crushing injury on the seat, hard plastic [or even projectile in the car] in front of them or not).
If any of this is foreign to you and you have kids in car seats or shuttle them around, The Car Seat Lady has some great tips:
http://www.thecarseatlady.com/vehicles/the_latch_system.html. Cheers and feel free to hit me up with any car seat questions you may have.