The
Trucktrend web site has posted a fairly interesting/comprehensive article about what steps manufacturers are taking to squeeze more MPG from recent pickups in response to customer demand, the threat of rising fuel prices, and tightening fuel economy rules.
Let's get this out of the way first: the title - "
Good to the Last Drop: Getting the Most Possible Mileage Out of a Pickup" - is ridiculous, of course. Obviously they're
not getting the
best possible mileage. Truck makers are notoriously conservative, and the spectre/excuse of "consumer acceptance" plus fear of halting/reducing the ever-increasing towing/payload specs keeps them from doing anything beyond incremental changes.
But the article does cover a wide range of tweaks, and interestingly it quantifies many of them in terms of effect on MPG.
Weight reduction:
- aluminum lower front control arms and 17-inch aluminum wheels on the GM XFE trucks
- GM says "about a 0.7-mpg (EPA combined) benefit per 500 pounds in weight savings."
- Toyota says: "A 50-pound weight reduction is worth about one percent in fuel economy."
- Nissan says: "Reducing its weight by 100 kilograms (220 pounds) can boost economy by about 1.5 percent"
I wonder why the formulas disagree. I suspect it's the way the article was written (no context - city? hwy? combined?), rather than fundamental differences between the companies.
Improved aero:
- better initial design, aided by CFD and wind tunnel testing
- GM’s XFE pickups have lowered suspension, bigger front air dams, and OEM tonneau covers - " the tonneau cover gives a 0.1- to 0.2-mpg improvement, the air dam maybe 0.05 mpg, and the slightly lowered suspension another 0.05 mpg. "
- Ford: "aerodynamic improvements on the 2009 F-150s average around 15 counts, or 0.015 Cd. “That 15-count improvement gets you on the order of 0.12 mpg highway"
It's funny that each of the Big 3 manufacturers claims "best" drag coefficient for at least one of its pickup models (depending on style, eg. whether it's a crew cab, long box, short box etc.).
Nissan's engineer comes across as the most pessimistic of the lot:
Quote:
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“But a 10-percent [aero] drag reduction is almost nonachievable,” he adds. “That is drastically changing the style of the body. In the real world, two or three percent is really tough for us. And 100 kilograms of weight is almost a hopeless number. That is almost downsizing the truck, which is really tough. Honestly, 1 mpg is a huge number for me.”
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Engine mechanical & calibration:
- DCFO WTF?? Am I reading this right - is deceleration fuel cut-off (DFCO) really a NEW feature in some truck engines?? "Ford F-150: Among these are such fuel-saving features as open valve injection and deceleration fuel cutoff on 4.6- and 5.4-liter V-8s."
- Also in the Ford: "a substantial 0.5-mpg gain comes from lowering engine idle speeds by about 100 rpm"
- Dodge added variable valve timing to the available 5.7-liter Hemi V-8 engine, which already had Chrysler’s cylinder-deactivating Multi Displacement System. All this achieved an average 1-mpg improvement over 2008 models
- Toyota's variable valve timing reduces part-load pumping losses
- Nissan: friction-reducing measures as piston ring coating and camshaft microfinishing
Engine accessory:
- Ford: high-efficiency alternators
- Ford: changed pulley ratios on power steering pumps, and changed water pumps in the engine to make them more efficient
Transmissions & final drives:
- taller rear axle final drives all around
- six-speed transmissions: "the F-150’s new six-speed automatic contributes roughly a 0.25-mpg improvement"
- Nissan mentions a CVT
LRR tires
- Several trucks use them, and Nissan says: "Reducing rolling resistance by 10 percent can get you 0.2-0.3 percent better economy."
Full article:
Good to the Last Drop: Getting the Most Possible Mileage Out of a Pickup - Consumer Feature - Truck Trend