As shot, Huntington Beach car show in Central Park. Minor overall adjustments and capture sharpening in Lightroom, then export to Photoshop.
New layer with only the car selected; background hidden.
Two layers inserted under the car: one 100% opacity black-and-white gradient with a car-color layer above it at 73% opacity and Linear Burn blend mode.
Two more layers remove the small front-window sign and the license plate. I don't think the plate would be a legal or privacy problem, but it just detracted from the sleek lines of the car.
Six curves layers adjust contrast in the roof-top stop light, rear deck, left and right taillights, left and right grilles, and tailpipes. Final crop and vignetting are done in Lightroom, along with color adjustment for printing.