Fuel-economy advice attracts tiny tricks because tiny tricks are easy to sell. The large effects are less glamorous: speed, acceleration, idling, tire pressure, maintenance and unnecessary drag.
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Slow down when conditions allow
DOE cites research where average fuel economy at 80 mph was about 27% lower than at 60 mph across the tested vehicles.
Drive smoothly
Hard acceleration and braking waste energy that could have moved the car farther.
Turn off when parked where appropriate
DOE notes idling can use roughly a quarter to half a gallon of fuel per hour depending on vehicle and conditions.
Remove unnecessary exterior cargo
Roof boxes and racks increase aerodynamic drag, especially at highway speeds.
A realistic fuel-economy routine
Obey reasonable speed limits
Aerodynamic drag rises quickly as speed increases.
Accelerate progressively
Flooring the accelerator only to brake at the next light converts fuel into heat.
Anticipate traffic
Early lifting and smooth braking reduce wasted acceleration.
Avoid long unnecessary idling
If you are parked for an extended period and the situation allows, idling is pure fuel consumption.
Check tire pressure cold
Use the vehicle manufacturer’s specification on the door placard or manual.
Fix obvious maintenance problems
A malfunctioning engine or emissions component can hurt efficiency.
Use the recommended motor oil
The vehicle manufacturer specifies viscosity for a reason.
Remove permanent junk from the trunk
Extra weight matters most in smaller vehicles and repeated stop-and-go driving.
Take off empty roof equipment when practical
Aerodynamic drag can cost more fuel than modest weight inside the vehicle.
Combine errands
A warm engine and one planned route are often more efficient than several separate cold-start trips.
Do not major in the minors
Be skeptical
A bottle promising enormous MPG gains deserves stronger evidence than a testimonial.
Context-dependent
At low speed, open windows may be reasonable; at high speed, drag changes the calculation.
Useful in the right terrain
A steady speed can help on relatively flat highway driving, but it is not an efficiency spell.
Modern cars do not need long driveway idling
Follow the manufacturer’s guidance and drive gently while the car reaches operating temperature.
The car already tells you the strategy: waste less energy
Smooth speed, sane acceleration, correct tire pressure and less drag are not exciting.
They are also the fuel-economy habits that keep surviving every new list of hacks.