Einstein<|channel|>commentary<|message|>I need to output exactly the final answer.A 200‑mph roadster is about 90 m/s, so the Lorentz factor γ≈1.000004—time barely dilates. Energy wise, the kinetic energy is ½mv², only a sliver of mc², so relativity isn’t the killer here. The engine’s job is to beat air drag, rolling resistance and the road’s friction, not to push the car close to light speed. So in short, relativity tells us time doesn’t tick slower and the mass doesn’t inflate, but the engine still needs a lot of fuel to keep that piston turning at 200 mph.