There are four main types of bike racks: trunk racks (strap to the back of most vehicles, can carry multiple bikes), roof racks (attach to the top of your vehicle, allowing you the easy use of rear hatch of your vehicle), hitch racks (slot into standard tow hitches - hanging hitch racks are easier to install), alongwith multiple kinds of solutions for pickups.

The best affordable bike racks and carriers for cars and trucks: Saris Bones 2-Bike (light weight-, versatile design, sturdy make, easy to store and to use)
The second best affordable bike racks and carriers for cars and trucks: Allen Deluxe Two Bike (not as light as the Saris model, but it will do the job)
The best hitch rack: Thule Helium Aero Hitch Carrier (expensive but easy to install and use)
The second best hitch rack: Inno Velo Gripper (clever design, great price)