Getting 35 MPG

Engine Control Computers
More powerful and precise engine control computers are available, but remain a bit too expensive for economy cars. As with all things electronic, as production rates increase, costs will drop and these computers will find their way into lower cost cars.

Hybrid Technology
Several varieties of hybrids will help boost fuel economy. Most current hybrids use their electric motor mainly to improve acceleration without hurting fuel economy. Future hybrids will give up power for fuel economy. Also, “plug-in” hybrids will use cheap household electricity to charge their batteries. Further down the road are hybrids that will use the electric motor for propulsion and a tiny gasoline engine only to charge the battery. For these to reach their full potential, there must be a breakthrough in battery technology. The current nickel-metal-hydride (NiMH) batteries are too heavy to store an adequate amount of electricity. Lithium-ion (Li-ion) batteries are lighter so offer the potential of storing more energy. Potentially, these could have enough electric-only range for most commutes and errands. The auxiliary engine would engage only for longer trips.

Can Your Mileage Get Worse?
There are also ways to get worse fuel economy, said Hubbard. Switching to higher viscosity oil or running regular-grade fuel in an engine designed for premium are two, he said. Many think they are helping the endurance of their engines by switching from the recommended 5W-20 to 10W-30 or even 10W-40. The exact opposite is true. Many engines employ extremely tight clearances in such areas a crankshaft and rod journals. Not only does the thicker oil require more energy to move when it’s cold, but it may not fully reach areas of super-tight clearances.


“When I was building race engines, I was happy to get an 0.025-inch tolerance on the rod journals,” said Hubbard. “Now some engines have 0.0008 clearances.”


While engines with 10:1 or higher compression ratios will run on regular gas, their mileage suffers, said Hubbard. When running lower-octane fuel, the engine computer retards the timing of the spark plugs and camshafts so that the engine doesn’t hurt itself. In the old days, low-octane gas would cause the fuel to self-ignite much like in a diesel. The driver would hear knocking or pinging, an indication that the engine was destroying itself. While today’s computer-controlled engines don’t allow damage to occur, they must work harder with regular gas to achieve the same performance as with premium. In one specific car, a Lexus RX400h, Hubbard has seen a decrease from 31 mpg to 22 mpg when regular gas was used. “You’re pushing the pedal harder to climb the same hill,” said Hubbard. “You’re costing yourself money by using regular.”