Will this diffuser scrape on steep inclines or driveway approaches?

The two-piece design mounts at factory anchor points, maintaining the same ground clearance as the OEM rear bumper. Take the same approach angles you normally would — the diffuser extends the visual line without adding ride-height risk.

Does this add any functional downforce, or is it purely cosmetic?

This is a styling diffuser. It adds visual aggression at the lower rear and complements the Volt aesthetic. For measurable aerodynamic effect, rear wing or splitter combinations are needed — this piece enhances the look.

What prep is needed before painting?

Sand the surface with appropriate grit to scuff the finish, then wipe clean of dust. Apply your chosen primer and topcoat system. Reference your paint supplier's prep steps for FRP to ensure proper adhesion and finish quality.