What is the name of this part This part is usually used on the simple 4 wide car base mostly seen in city sets.
With making these simple cars, it sits on the sides, and provides a base under a 1x4 Panel pieces. 4 studs on the lower part, 1 higher stud on each side which touches with the fender pieces. Dimensions for this piece is 1x6x1.
BrickLink calls it Part 52501 Slope, Inverted 45 6 x 1 Double with 1 x 4 Cutout: