The invention relates to the field of cars and discloses a four-planetary-gear-train automatic transmission and a car. The four-planetary-gear-train automatic transmission comprises four planetary gear trains, four clutches and two brakes. A gear ring of the first planetary gear train is connected with a planetary frame of the third planetary gear train, and a planetary frame of the first planetary gear train is connected with a gear ring of the second planetary gear train; a planetary frame of the second planetary gear train is connected with a gear ring of the third planetary gear train, and a sun gear of the third planetary gear train is connected with a sun gear of the fourth planetary gear train; a gear ring of the fourth planetary gear train does not participate in rotating, power input into a component is selectively transmitted by the first clutch to the gear ring of the second planetary gear train, and power input into the component is selectively transmitted by the second clutch to a sun gear of the first planetary gear train; the planetary frame and the sun gear of the fourth planetary gear train are selectively connected by the third clutch, and power input into the component is selectively transmitted by the fourth clutch to the planetary frame of the fourth planetary gear train; and the sun gear of the first planetary gear train is selectively braked by the first brake, and the gear ring of the second planetary gear train is selectively braked by the second brake.