There is a good reason why you all are getting such poor mileage...
In this day of high gas prices, it is amazing that so few drivers are changing any of the habits that have led to unnecessairly low mileage figures all along.
What are the major contributors for the actual mileage your vehicle gets? Well, to state the obvious, it is one part driver, and one part vehicle configuration.
1. Vehicle configuration: Every motorized vehicle built by a major manufacturer has certain inherit limits to the mileage it can obtain. These limits are dictated by certain key design elements that cannot be escaped unless the vehicle is modified in some way. Following is a brief run-down of the key design elements that most affect mileage:
A.) Vehicle Weight - A car that weighs 2,500 pounds has a better chance of better mileage than a car with similar porportions that weighs 4,000 pounds. However, a very sleek vehicle that weighs 4,000 pounds might get very good mileage, even with a large engine, given some other elements are in its favor. But overall, a heavier vehicle struggles to obtain the same mileage of a welterweight.
B.) Engine size and configuration - Put an efficient, 120 hp four cylinder motor in a 4,000 pound car and watch the gas needle move with haste. The engine needs to be more than efficient; it needs to be properly matched to the car. However, overall, smaller motors suck down less fuel than larger motors. The more cylinders you have to feed, the more fuel is required. No way around it. But keep in mind that the Chevy Corvette, with a 400 hp V8 can easily see 28 mpg on the highway, provided it is driven sanely. There are tons of "rice burners" out there that never see 28 mpg on the highway, so more factors than just engine size makes up the whole mpg picture.
C.) Coefficient of Drag - known in the industry as "cd," your car has an assigned cd that is derived from wind resistance and power loss due to that inherent wind resistance. For example, a large 15 passenger van may have a cd of 45, whereas the aforementioned Corvette has a cd of about 29. A cd lower than 28 is rare, and most modern cars shoot for a cd in the low 30's. Total frontal area, mirror shapes and sizes, vehicle height (ground clearance and overall height), roof racks, and grill design, among other external design elements, all affect the cd rating. Most trucks have a poor cd number due to their overall massive design and flat fronts. This is why you see cd ratings dictating design in the automotive world. Everyone wants their vehicles to be as sleek as possible so that they can achieve better mpg numbers, and to reduce interior noise. Either way, a high cd number hurts highway mpg numbers no matter what.
D.) Gearing - In the "old days," almost all cars had a 3 speed transmission. "Overdrive" was unheard of except among 18 wheelers. Finally, after eons of time passed, auto makers finally decided to begin installing overdrive transmissions into cars. So, what does an "overdrive" do? Well, the term overdrive means that instead of having a direct 1:1 final drive ratio (one engine revolution for one differential revolution), in overdrive, you lower the engine revolutions, much in the same way a 10 speed bicycle, through gearing, can give the rider greater speed without having to pedal faster. Lower engine speeds equals less frictional losses internally, and lower fuel consumption. So, a vehicle with no overdrive, or with a very conservative overdrive, will suffer mileage woes compared to a vehicle that has a "tall" overdrive (low rpm's at highway speeds).
There are other, less influencial factors, but those are enough to make the point. So, what is the best case scenario for achieving top mileage? Easy! Just get yourself a very sleek, very lightweight car with a small, efficient motor teamed with a transmission with 5 or 6 gears and a tall or multiple overdrives, and high mileage may be in your future.
As for a reality check, the makers of your vehicle have made compromises in all 4 areas mentioned and what they came up with in terms of vehicle parameters will greatly affect your mileage numbers.
But, there is one other major contributing factor -- YOU!
2. The Driver: Even the most fuel efficient car can get sucky mileage when in the hands of a lead footed driver. There are tons of you out there getting 14 and 16 mpg when 18 and 20 is easily obtainable, if you would only stop throttling it everywhere you go! Americans are some of the most lead footed, impatient, and drag race-oriented drivers in the world. And more often than not, the person next to you that seems to be trying to warp time is not some pencil-necked teen boy, but a youngish, cell phone talking, makeup fixing soccer mom who knows nothing of using a blinker or how to make a proper turn.
Seems like everyone is running and gunning like there is no tomorrow, and when gas is $4 a gallon, you would think there would be a little more caution applied in the right foot. But no, Americans are all drag racers, rushing off to make the most of their self centered days filled with senseless activity and deplorable relationships. And their mileage just plain sucks. But do they care? Guess not.
If, by some miracle, you would like to make a few changes in your personal driving habits so as to reap the benefits of greater mpg, here are a few basic hints:
A.) Accelerate modestly - In city driving, your mileage is almost 75% determined by how you accelerate from a stop. Gun it, and mileage goes down dramatically. Ease off the line and accelerate in a linear fashion, and you may start getting mileage you never knew was possible.
B.) Learn to coast - if you don't know what this means, it implies that there is always some time that passes between letting off the gas pedal, and applying the brake pedal. Most Americans always go directly from gas to brake, and brake to gas, with no time in between. If that is you, then your mileage is far worse than possible and you are to blame. When you are coming upon a red light or stop sign, just ease off the gas and coast for a bit. It saves your brakes and improves your city mpg and besides.....you have to stop anyway, so why not just ease off and enjoy the ride?
C.) Be Consistent - avoid stabbing the throttle. Ease into, and off of, the gas pedal, find a speed that is safe and legal, and with great finess, maintain that speed. The "rabbit" next to you gunning it will have to stop at the next red light like you do, so don't worry about him. THINK about your driving and work at being fluid and consistent.
D.) Lay off the brakes - Goes with coasting and being easy on the gas. Use your brakes to stop, but not to slow down. If you are paying attention and maintaining safe distances, you can moderate your proximity to other cars via gentle and calculated throttle inputs. Look ahead for brake lights, and when you see them lighting up coming towards you, ease off the gas and prepare to stop. Keep in mind that repeated stabbing of the brakes cuts mpg heavily, so be fluid!
Half of your mpg figure is determined by the vehicle designer, but the other half is up to you. Put down the cell phone, set aside the cola, tell the kids to shut up, and think about your driving. Slow down, ease up, become more fluid with finess, and watch your mpg numbers climb.
Drive precise!
