LEGO Chevrolet Impala SS instructions. This design represents seventh generation Impala SS. There are few limitation to this design, but I don’t think it can be any better in 6 stud wide City scale.
1.Because of shifted front headlights/bumper this design needs modified 1×2 plate 32028 above wheel arches, so side line fully connect to headlights. And because of railing there are small gaps near to headlights (visible in first render image).  2. Front bumper may look a bit oversized but it fits better than normal sized versions. 3. There are no wheel arches in this design, and wheels are a little bit outside of vehicle dimensions. 4. Because of low roof design minifigure can’t sit straight up, so it needs to be angled down to fit inside, and even with that in most cases it needs to be without hair piece to fit under roof.

LEGO Chevrolet Impala SS MOC info:
– 6 stud wide
– same scale as official LEGO City/Speed Champions models
– simple design
– seating for 1 minifigure
– total 181 parts from 53 lots, all parts will cost around $15

You will get Bricklink source file that can be used to find parts automatically on LEGO part marketplaces like Bricklink.com
And PDF format instruction file.