I've been staring at the press release images of the 2014 Impala, and I have to think the best modification for this car would be an entire drivetrain transplant and a proportion overhaul - no small task in real life. With the power of photoshop however, this overgrown antelope can easily benefit from a 400 lb diet.
Photo modifications include: vehicle lowered ~1.5", sectioned ~2", with bodyline proportionally raised .75" overall, and .5° of forward rake added to bodyline. Greenhouse reduced in all directions & moved rearward, front wheel size reduced ~1", and front door cutline moved rearward 2.5". Lightgroups and door handles have been shifted, not modified.
I think the result is rather fetching.