Preformed vs. Sewn

• Almost all modern automobiles use preformed carpets, which conform directly to the shape of the vehicle's floor and come precut to fit. Preformed carpets are more expensive and more difficult to find for some applications, but are exponentially easier to install and generally better looking. If you can find a preformed carpet in the color and style you like, then get it; the labor required to custom fit a universal carpet quickly offsets its price advantage. Still, universal-fit carpet may be the only option if you're looking for a non-factory color or style.
  
  

Cut or Berber

• Berber isn't a brand name; it's actually a term used to refer to a style of carpet that uses loops of fibers instead of cut fibers. Manufacturers produce cut-pile carpets by gluing carpet fibers end-in into a backing material like rubber or cloth, then going over the carpets surface with a type of "lawnmower" to even it out. The Berber carpets loops make its fibers much stronger and more resistant to wear, but they also make it less plush and comfortable. You can use a cut-pile carpet in your car; just make sure to use rubber heel-pads or mats in high-wear areas like the floorboards.
  
  

High vs. Low Pile

• High pile or "plush" carpets offer more comfort, better sound and heat insulation and greater luxury, but they also mat down easier and are harder to keep clean. Dirt and muck can get trapped so far under the carpet pile that it may not come out using a standard vacuum. If you're going to use a high-pile carpet instead of a short nap, then plan on regular carpet cleanings to keep the nap looking good. Bear in mind that deep-pile carpets also trap moisture, so add a little fungicide to your shampoo before cleaning to prevent mold and mildew due to trapped moisture.
  
  

Rubber-Backed vs. Cloth-Backed

• Rubber-backed carpets are heavier and more expensive than cloth, but they do offer a number of advantages. Rubber is a fantastic heat, moisture and sound insulator, and adds a bit of "plush" to your interior. A foil-backed insulating pad and some cushioning will do the same thing, but offer less protection against moisture. Rubber-backed carpet effectively forms a solid barrier between the interior of the car and the metal floor, so any moisture that makes into the car from spills or rain won't get trapped and serve as a breeding ground for rust and mold.