Like everyone else said, speed - or more accuratly, rpm's - probably have the most effect on mileage. if I cruise along at 1800-2000 rpms, I get 19-20mpg. Last winter I was driving through a snow storm - 40 mph in 4WD - and managed 23mpg. effective, but boring. Back and forth to work at about 70mph, I get 17-18.

 

There is a difference between getting the best mileage, and improving the mileage for your style of driving. The latter is what most people are after.. That really only comes thru altering the motor thru tuning or hard parts, assuming proper maintenance.

The difference between skilled and lazy. The former is worth 30%, the latter maybe 10-15%. The cost difference is $0 versus $1,000 plus a very long term payback. FE is a sub-set of Overall Ownership Cost. Improving FE is generally only a few cents from an accurate cents-per-mile calculation.

Skill acquisition (a mental attitude in main) is easy enough when I make the decision to follow certain principles, such as:

Never Stop

where some route planning to avoid stop-n-go on the one hand, and learning to "time the lights" by coasting, etc, keeps me from having to move a 7,400# truck from a standing start. FE is high at cruise, but abysmal from stops due to vehicle weight.

I know I'm being successful by recording higher average miles-per-hour from the overhead display record of engine-on hours (per tank; reset).

If I can maintain 27-mph or higher in average mph, mpg in town is very good.


Never Idle

Commonly misunderstood. This is not zero mpg. This is negative mpg. Drags down average mpg and mph very quickly. Those tenths of a mpg slowly getting higher and higher on a long trip drop like a rock with only a half-hour total time of idling (per tank of fuel). Idling drops average mph, an excellent indicator. (The new Fords break out idle time from the overall engine hour operating time!!).

Avoid drive-thru, trying to park close to the box store entrance, etc. Park in such a manner as to pull out to the appropriate exit to the street (some are better than others). Small stuff that adds up, in other words. My mpg numbers drop below 20 in town during summer due to the high heat. (Hotter is better for FE, but not for idling with A/C on MAX). Your number may drop for winter. But winter drivers can get around extended idling more easily (block heater, clothing, etc).

The only way to know anything works to produce increased FE is through records. One must know average mpg not a few tanks that are better. Takes a few thousand miles of recording every drop of fuel. I keep a log in the console and fill it out at every fuel stop. Takes all of 1-minute.



So far as I can tell, tuners are good for the acceleration phase. There are plenty of guys getting 24-26 mpg highway with the right spec truck in favorable climate and terrain. I have yet to see those achieving 28-mpg under extended highway travel. Maybe tuners should be classified as "driver foolers" (better engine timing map). I'm not wholly against them, but I'd like to see a few thousand miles of highway-only fuel use records before wanting to shell out $$$.

While a Smarty and a new cam might be nice, the payoff will be in years, it at all. As both are non-stock, the question of longevity & reliability is in question, a much bigger Economy problem.

Utilizing a few principles, on the other hand, means that I'm increasing skill level (making more decisions of a different kind) that will even out after a period for no money at all. If I won't do it, it matters not. If I do, I am paid in cash, immediately.

As most of us cover the same routes for 90% of our driving (according to the DHS, tracking us via cellphone GPS), it's not difficulty to analyze best routing (as does UPS) and, say, use only right-hand turns for the usual weekend errand running. Etcetera.

We've all heard it said: Plan for the worst, hope for the best. If fuel went to $10/gl and purchase amount restricted (as in 1979), well . . some practice now will mean the most. Can't just "slow down" and do much better. A CTD is capable of a deeply impressive amount of work for a pittance of fuel. But it takes some work, a different mental attitude.

A man will find that he will know -- without having "worked for it" -- the number of brake applications on his familiar route. He's cut them to the minimum, and -- barring disaster -- his driving will be smoother and in all ways easier. If one wishes to remain as stressed as the sheeple in simple driving around, then continue to drive like them.

Another indicator of better FE is higher miles per brakes and tires. Anything less than 70k for either (which is low) indicates the need for remedial driving instruction.

Driving for fuel economy is tantamount to driving for longest vehicle life. And it's corollary is that driving safely also comes as a natural result.

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