+6 on weathertechs.
I have them for the front and rear passengers (not cargo area though, use a moving blanket there just in case I need a blanket to not freeze to death "just in case").
They stay anchored really well (car wash folks actually pulled out one of the anchors on the driver side, sigh) and hold liquids (soda), snow and rocks. When clean, they look nearly brand new and you don't have to worry about them sliding and jamming the gas pedal.
There are generic versions around (w/o the Weathertech logo) but as a long term investment, they are hard to beat.