l have 2001 lexus gs 430 with 40k miles on it and gas price is way high. what should l do?
how l improve mpg using newer better muffler or engine tune-up?

Trade it in for a scooter, or something with better gas mileage

Not much. 1. Keep the tires inflated properly; that makes a big diff. 2. Do not carry anything u do not need.keep it light. 3. Use the lowest octane fuel that will work without the engine making noise(knocking or pinging). 4. Never use a roof rack! (Skis or bike, luggage etc) 5. Do ur maintenance on time/keep the thing tuned. 6. Do not jackrabbit start. (making the tires go real fast from a stop) Get quickly to the speed u want & stay there. Changing speed uses more fuel. 7. Slow down. After about 55 MPH most vehicles start using relatively much more fuel. 8. Use the air conditioner & keep the windows closed. Newer car air conditioners r very efficient but old cars were not so some old timers will tell u to not use the air but that is only for older models. 9. Do not leave the engine running when you're not moving. 10. Do not warm-up the engine in the morning to clear the ice. Use a scraper, drive slowly until the engine warms.(but make sure u can see)

Park it and walk.