In a follow up to the CAFE standards blog done last week, the Carlocate.com crew was wondering what it would take to make a car using primarily an internal combustion engine to achieve a 54.5 mpg corporate average. Apparently Forbes.com was thinking the same thing as us and compiled some ways that a combustion engine could achieve that 54.5 mpg mark by 2025. Here was what they came up with:

• Weight Reduction: The more mass, the more fuel it takes to move it, the less mass the less gas it needs. Mark Ross, a Professor of Physics at Michigan says, “decreasing a vehicles weight by 10% enables about a three percent increase in fuel economy.” Expect manufacturers to cut weight using carbon fiber, plastic, and aluminum instead of heavier materials.

• Slipperier Aerodynamics: At highway speeds, over 50% of the engine power goes to overcoming wind resistance. Therefore, cut down wind resistance and lower fuel consumption. Expect to see less blocky trucks and SUVs in the future.

• Turbo-charging and Direct Fuel Injection: While Ford already does this with their EcoBoost engines; expect to see more manufacturers reduce engine size and add turbochargers and direct fuel injection. This cuts down on the engine size while retaining the power of the larger engines.

• Variable Cylinder Management: For example, a V8 will only use four-cylinders until it needs extra power where it uses all eight-cylinders. Honda currently uses VCM with their V6 Odyssey and Accord which can run with three, four, or six cylinders.

• Automatic Stop-Start: Your engine shuts off while the car is stopped which can boost gas mileage by about 15%.

• Mild Electrification: Using a small electric motor to assist the combustion engine, while never actually powering the car on its own, classifies this car as a “mild” hybrid. The small electric motor provides extra power while using energy from braking to power the engine instead of more fuel.

• Electric Power Steering: Replacing the belt driven power steering, this system adds less drag to the engine while improving handling.

• Regenerative Braking: A system used in hybrid models that recovers energy from the car braking to charge its batteries to provide more electric power.

• Advanced Transmissions: More gears equals more launch power and less power needed for cruising speeds, cutting down on fuel for each stage. Expect to see more Continuously Variable Transmissions as they weigh less than standard transmissions and provide more instant power.

• Diesel Power: Diesel engines produce more than 20%-25% greater fuel efficiency than gasoline and with better torque. With clean diesel technology, these engines are also able to comply with emissions regulations in addition to assisting with CAFE standards.