The mass exodus from SUV’s and pickup trucks has begun. It takes power to haul around those behemoths, and larger displacement engines cannot approach the fuel economy of their more svelte counterparts. To put things in perspective, a 5,000 lb vehicle needs an engine producing 300 horsepower to obtain the same performance as a 3,000 lb car with 180 horsepower.

Ford Escape 34mpg city

Image courtesy of Ford Motor Company

If you want a peek into where the auto industry is heading, look no further than commercial transportation. The livelihood of the trucking industry hinges on fuel economy, and one look at today’s trucks will tell you what changes are in store for automobiles and light trucks. Diesel contains more energy than gasoline which translates to better fuel economy. Modern big rigs are powered with engines sporting such features as turbocharging and Diesel Direct Injection. These technologies allow an engine with much smaller displacement to do the same amount of work as an engine with much larger displacement but lacking the efficiencies and technology of its little brother.

Image courtesy of Ford Motor Company

So, what is on the horizon? Look for a wave of low-displacement (1.8 to 2 liter) 4 cylinder cars and trucks sporting, you guessed it, direct injection and/or turbochargers. Direct injection improves efficiencies and power by allowing higher compression due to the superior burn obtained by placing the fuel injectors directly into the cylinder head. Higher compression increases torque across the RPM range. Direct injection in conjunction with a drive by wire throttle and computer control allows engineers to eliminate restrictive throttle plates to adjust engine speed. Instead, speed is controlled by adjusting the air/fuel mixture ratio which is more efficient under power and far more efficient when your foot is off the gas pedal. Also look for lightweight steel alloys in doors, trunks and hoods to trim weight and increase fuel economy.

Turbocharging is virtually free horsepower as it uses a turbine spun by exhaust gasses to pack more air into the intake system. Roughly speaking, adding 10 PSI of boost from a turbocharger will increase horsepower and torque by approximately 50%. Gains would be better, but higher intake temperatures due to the compression effect of air along with required changes to ignition timing reduce power slightly.

Questions to Ask Yourself

Restrain from purchasing a truck or SUV if a car will do. Don’t buy a 4 wheel drive car if front drive will suffice. Putting power to four wheels increases losses from friction, etc, and modern all-season tires are capable of navigating front-drivers through all but the nastiest winter snows.

Don’t be sentimental when it comes to your daily driver. Older cars pollute far more than today’s vehicles. That 1965 VW Bug may have a special place in your heart, but it emits more hydrocarbons and carbon monoxide than any modern gas-guzzling SUV.

What to Look for

As speed increases, proportionally more power is required to overcome air resistance. Remember all that fuss over drag coefficient ? Drag coefficient is only one part of the equation. Total drag is calculated by multiplying frontal area (imagine taking a snapshot of the front of a car and measuring what constitutes car in cubic inches or centimeters) by drag coefficient. The lower the drag, the better a car or truck’s highway fuel economy, everything else being equal.

Take heed of the vehicle’s capacities. It is less expensive and more sustainable to replace 3.5 quarts of oil than 6. Replace filters at required intervals, and use synthetic oil to reduce fuel consumption and increase the life of your engine and vehicle. Wax your car regularly to reduce drag, and polish the windshield using a product such as Rain-X .

Don’t purchase too little power! If you’re constantly piling 4 kids and a golden retriever into the car to head to soccer practice, a subcompact with a weak engine won’t be any more fuel-efficient than something properly sized with more power.

Knowledge is power! Arm yourself with information before venturing into the lots of dealers. If a salesperson cannot answer your questions competently, ask for a supervisor.

Lastly, don’t purchase something you are not happy with. Who cares if you bought the greenest guy on the lot if it brings you no joy.