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40MPG: YMMV

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Many automakers and the EPA ratings, claim that some of these newer fuel efficient cars are good for 40 miles per gallon. While this number may somewhat misleading, it turns out you can get these efficient cars to achieve better than 40 MPG's by driving smoothly. Lets take a look at this issue and what you can do to save a boat load of money on gas, reduce your emissions and keep your car running as smoothly as possible. 

To be fair, many manufacturers only claim that ~40MPG's is the highway rating of their fuel thrifty vehicles. Can you actually get 40MPG's from a Hyundai Elantra, Volkswagen Passat, or Ford Fiesta Eco-netic? Yes, but only if you drive with a light foot on the highway. Actually many cars can get much better than 40MPG on the highway if you drive them smooth and steady and resist going faster than 50MPH. Like they say YMMV (your mileage may vary).... the good news is that you can get much better than 40MPG's if you are driving calmly and carefully. There are simple things you can do to boost your MPG results.

Vehicle Related MPG Enhancers

1. Take out any stuff in your car that you don't need to be towing around with you. You might be surprised at how much all of those small items weight together. According to the EPA, for every 100 lbs you remove from a vehicle, the fuel economy increases by 1 or 2 %.

2. Keep the tire pressure normal. You can improve you gas mileage by over 3% by keeping your tires inflated to the proper pressure. Every 1 PSI under the OEM recommendation lowers you fuel economy.


3. Avoid using your HVAC system. If you are driving less than 50MPH, cracking two windows, one in front and one in back, can create good cross flow ventilation. The AC compressor is the major energy hog in most vehicles. At speeds above 50MPH, keep the windows closed and use the vent system in the dash. Using defrost modes (AC) or air conditioning can lower your fuel economy by 10% or more.

4. Maintain your car. A properly tuned/ maintained engine with fresh oil, a clean air filter, good compression, and good ignition is up to %5 more efficient than an engine that is out of tune. The other tree are free options, this one is part of "good" car ownership and costs money. You can expect to throw   thousands per year at a car to keep it insured, maintain, and fueled up on safe tires. You can obviously save a lot on depreciation losses by purchasing lightly used vehicles, but be careful to have them inspected. Your total cost per mile for driving depends on a lot of facts: figure them out and figure out what your car is really costing you.

5. When you change your tires, try some LRR (low rolling resistance) versions. In a 20MPG vehicle, they will save you more than $400 during 50,000 miles of operation, effectively paying for the tires. Bridgestone Ecotopias or Michelin Energy Saver A/S for example.




Driver Related MPG Enhancers 

Gentle on the gas pedal and gentle on the brake pedal. The driver has the biggest effect on fuel economy. Aggressive drivers not only wear out their vehicles faster, they also observe fuel economies far lower than the EPA rating of their vehicles. Irrational dangerous aggressive driving burns through tires, brakes, and fuel much faster than intelligent safe conservative driving. I am not talking about driving super pokey slow to the point of irritating other drivers, I am talking about calm smooth steady careful driving that requires thoughtful restraint and control.

Many newer cars will give you some form of "eco" feedback to let you know if you are driving "fuel efficiently". The trick here is to drive carefully and smoothly. For example not racing to a stop light, or red tail lights, think smooth and steady. Imagine you had fragile cargo (you do, you or you and your passengers), and you are trying to keep the philosophical egg balanced on the dash board. Driving smooth and steady, especially on the open road, will result in better than EPA fuel economy results.

My father and I took a trip in our 1992 Subaru Legacy sedan from Seattle to Olympia recently (about 70miles one way). Normally, if I drove like the average person does on I5, the Subaru returns about 28MPG on the highway (24 in mixed city driving). By going 50-55MPH the whole way, we got 38MPG's. This car is over 20 years old and has north of 160,000 miles: thats 8MPG better than the 30MPH highway it was rated at when it was new. No special tricks, just smooth and steady 50-55 MPH in the right lane. It turns out that aerodynamic (wind pushing) losses are much greater at speeds over 50MPH. Most vehicles, including our subaru have an aerodynamic coefficient (CD) of 0.31 or higher. Keeping the high way speeds lower (around 50MPH) allows these relatively boxy vehicles to cut through the air without a lot of losses. Driving the same slower smoother way from Seattle to Olympia and back in my Prius returns close to 60MPG's.

Hypermiling is a term that describes "Driving techniques that allow you to achieve better than the EPA fuel economy ratings." Extreme hypermiling techniques can be dangerous (like drafting closes in the wind box behind a large semi-truck), but most of these fuel saving techniques are simple and come down to driving very calmly and intelligently. If you want to make a game out of beating the EPA rating for you car, then welcome to the Fossil Fuel conserving world of hypermiling :)


Hypermiling Techniques 

"Pulse and Glide" : this is really only possible in Hybrids and Manual Transmission cars. The idea here is to allow the car to coast as much as possible, where the Pulse is the "engine powered part" and the Glide is the "Kinetic Momentum" "coasting" part. In an automatic transmission car, the equivalent is gently accelerating to the speed limit and then driving smoothly to keep you car at that speed (slowing down and speeding up again wastes fuel, brake pads and tire tread). 

"Gentle Foot" Gentle acceleration, low RPM shift points, ect. If you are driving a manual, this means keeping the car in higher gears to take advantage of the longer gearing. If you are driving an automatic, the engine will automatically shift to a higher gear sooner if you are gentle on the throttle. 

"Early Soft-Brake ", this is where you preemptively anticipate an upcoming stop several hundred feet in advance, and gently apply the breaks softly so as to keep up your momentum by the time the light changes so you dont have to stop. This can be then combined carefully with "catch the light", a very similar idea which requires light signal analysis/ prediction and early soft brake.

"Catch the light" is where you slow down so as to still be moving when the signal allows you to go again, and that includes taking into account how many vehicles are stopped at the signal in front of yours and estimating how fast they will accelerate. If you can see the light from the previous light, this includes avoiding speeding up the maximum speed: your goal is to catch all the green lights so you never have to stop the car completely, only gently speeding up and slowing down. In a manual transmission, this will result in a lot less shifting :), in any other vehicle it will bost you city fuel economy by %20 or more.

"Wave Cancel" in heavy traffic you slow down to 2, 3, 4, 5, 6, 7, 8 or whatever really low MPH speed needed to avoid stopping and starting constantly: this can save your leg/ clutch in a manual vehicle: if you are careful to observe this, you will note that large trucks do that as a general practice. This is known as wave canceling in physics. Stop and go traffic formations can be viewed as "Standing Waves", where wave cancel seeks to cancer out the dips and crests (stops and starts). This requires leaving a buffer zone infront of your car, and do not be surprised if a bunch of impatient rude morons cut you off because they see an opening in front of your car (your buffer zone), when that happens, slow down even more to create another buffer and then enjoy watching the tool that cut you off mashing their pedal back and forth ( as you coast along nicely wave canceling behind them) : don't get smug about it either, your not that special! Everyone is Equal in Gods eyes... with wave canceling you do get to enjoy a car that costs less to operate because wave canceling reduces wear and tear on your car and also boosts your fuel economy. In stop and go traffic, this can result in a %20 or better fuel economy increase.

"Corning dubbing" where you deceleration ahead of a known corner such that you reach the safe cornering speed by the time you get to the corner without touching your brakes or the gas pedal. Ripping around corners to conserve your forward momentum will put more stress in your cars tires, and is totally inappropriate in wet or snowy conditions. The idea hear is to keep your speed so less gas is required to speed back up again when you clear the corner. Most cars can clear a tight corner with careful driving at 15MPH. Don't exceded your comfort level, or you will likely end up kissing the curb with one of your rims, knocking your wheel alignment out of balance.

"Hill Speed Jockying" where you gently accelerate to above the speed limit on when approaching a hill, and then back of the gas pedal a little to allow you vehicle to decelerate down to slightly below the speed limit as you crest the hill, then you can use gravity not the gas pedal to allow the car to speed back up on the way down, and on the way down, allowing your car to go slightly above the posted speed will slightly boost your fuel economy (use careful judgement here).


40MPG's : Sure

Combining all of the above tips will help you to beat the EPA rating for your car. If you drive more than 12,000 miles per year and are paying $4 or more per gallon for fuel, this will also save you a lot of money. Driving your car smoothly and gently will allow it to last longer with less mechanical problems. You can best most EPA estimates by %20 or better with the fuel saving techniques listed above.

Examples of beating the EPA Fuel Economy ratings can be found all over the internet. An Australian couple, John and Helen Taylor, for example, drive a stock diesel fueled manual transmission 2012 VW Passat 1,626 miles on one tank of fuel from Houston TX to Sterling VA, averaging an record setting 84MPG's.

Other high MPG fuel economy records have been set by Wayne Gerdes, for example he drove a 2011 Hyundai Sonata hybrid 2,269 miles and averaged 59MPGs. Look around online. Fuelly and Clean MPG's are sites where you can find other real world examples of great fuel economy in vehicles that get only normal fuel economy when driven thoughtlessly/ aggressively.

http://www.cleanmpg.com/

http://www.fuelly.com/


***Note the following ***

Diesel (with manual transmissions) tend to be very fuel efficient with a smooth operator... :)

Hybrid vehicles tend to achieve greatly improved city fuel economy, and good highway fuel economy in contrast to their non-hybrid equivalents.

Even CVT equipped automatic vehicles tend to be more efficient than their traditional automatic counterparts.

Smaller and ligher vehicles tend to be more fuel, tire and brake efficient then larger heavier ones.


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