New Tech Is Pushing MPG Up; Emissions Down

We frequently hear of the “all of the above” approach made possible with an alphabet soup of technologies to improve mpg and emissions and over the last half decade new tech has risen markedly.

According to the U.S. Environmental Protection Agency’s Trends report just released, powertrain technologies that once were rare are becoming increasingly common.

But despite the advent of all-electric vehicles, the majority of CO2 and oil savings from new vehicles is due to new gasoline vehicle technologies, only one of these being hybrids which comprise under 3 percent of new car sales, and plug-in hybrids at around 0.5 percent.

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While battery electrification advocates look to potential “game changers” to shift the paradigm, and other voices say we’re on the verge of a protracted fuel cell roll-out, it’s the plain old gas engine that’s still doing the heavy lifting for Americans.

The average window-sticker fuel economy of new vehicles sold in the U.S. in September was at 25.3 mpg—down 0.5 mpg from the value in August.  This large drop likely reflects the increased sales of light trucks and SUVs.

The average window-sticker fuel economy of new vehicles sold in the U.S. in September was at 25.3 mpg—down 0.5 mpg from August. This drop likely reflects the increased sales of light trucks and SUVs, but overall mpg is up 5.2 mpg since October 2007.

Except, there is not so much that’s “plain” or “old” about them. Unlike in Europe, Americans buy under 1 percent of diesel passenger cars, and while these are increasing, automakers are pouring their resources into a bag of tricks to clean up the gas engine’s act.

These technologies are so effective, they have allowed automakers to stall more-rapid development of electrification technologies. The U.S. EPA has previously stated only 1-3 percent of new cars need be the plug-in variety to satisfy 2025 federal requirements.

That’s a low bar to cross, and advocates hope to see more, and they may get their wish assuming California can enforce its ZEV rules mandating one in seven plug-in cars by 20125.

New Tech

Automakers are making engines smaller, more potent for their size, and less wasteful. How they go about teaching the old dog new tricks varies, but the EPA has highlighted progress for the last five years.

Two key engine technologies introduced more than a couple decades ago are variable valve timing (VVT) and multi-valve engines. These are nearly universally found on 2014 model year vehicles.

Another rapidly increasing tech is gasoline direct injected (GDI) engines. Engines with this technology are replacing port fuel injected engines – which themselves replaced carbureted engines from the 1970s and 80s.

Technology Production Share for MY 2009 and MY 2014. Source: U.S. EPA.

Technology Production Share for MY 2009 and MY 2014. Source: U.S. EPA.

GDI engines came along in 2007 as a rare technology, and by 2013, 30 percent of new vehicles had such engines, and the count for 2014 is expected to have 38 percent.

Another technology becoming rapidly more commonplace is turbocharging. Turbo engines have increased by five times the number that were sold in 2009.

Turbocharging is enabling the reduction of the number of cylinders, such as replacing a naturally aspirated six or eight with a potent turbo four.

However, automakers are also pushing the other end of the frontier with large V8s, and via turbocharging, achieving astronomical power output, with comparatively OK fuel economy.

Not to be left out in the powertrain equation is also the transmission. The percentage of vehicles equipped with six or more speeds and continuously variable transmissions (CVTs) grew from 37 percent in 2009 to 90 percent in 2014.

2014 is expected to see CVTs and transmissions with seven-speeds or more account for 30 percent of new vehicles.

Advanced Technology and Alternative Fuel Vehicle Models in MY 2009 and MY 2014. Source: U.S. EPA

Advanced Technology and Alternative Fuel Vehicle Models in MY 2009 and MY 2014. Source: U.S. EPA

Other tech like cylinder deactivation – such as used on the Corvette Stingray to enable 30-plus mpg on the highway – is growing less rapidly than multispeed trannies.

Also limited are hybrids, diesels, and EVs, as mentioned, but they have grown significantly since 2009 to nearly twice the number.

Of EVs and PHEVs, there are now 20, though not all are available nationwide.