I spent my career as an automotive engineer at GM. During my time in the auto industry I played a hands-on role in putting new technologies on the road, and had a front row seat to view how cars and trucks have become more efficient over time. That’s partly due to the hard work of my colleagues who design and manufacture vehicles and their parts—but also due in part to a strong set of federal standards that have helped drive the technology forward.
The efficiency and emissions standards that went into effect in 2012 have been a real success—they’ve saved drivers tens of billions of dollars on fuel and cut hundreds of millions of tons of carbon dioxide emissions. Unfortunately, that progress is at risk because the executive branch is trying to roll back these standards.
The Department of Transportation and the Environmental Protection Agency have proposed flatlining standards in 2020, meaning that cars and trucks wouldn’t need to get cleaner or more efficient. They say automakers can’t meet the challenge of increasing efficiency. They’re wrong—and I know because I’ve spent my career helping to improve their efficiency.
As a mechanical engineer, I designed automatic transmissions and their components. When I began nearly forty years ago, these were sometimes noisy and rough-shifting—and not particularly fuel-efficient. But over time, they’ve been transformed into an elegant enabler of vehicle fuel efficiency. These advanced transmissions go hand in hand with improved vehicle aerodynamics, lightweight materials, and fuel economy advancements in the engine and other vehicle components. By combining all these technologies, automakers have achieved vehicle fuel economy undreamt of when I started.
Many features have contributed to the transmission’s transformation, but perhaps the two most important are more speeds and electrification. Due to high mechanical efficiency, transmissions are more efficient than internal combustion engines when it comes to producing the wide range of wheel torque needed in vehicles. Having a high number of transmission ranges allows the engine to operate at peak efficiency, a key foundation of fuel economy. When I began, most transmissions were 3 or 4 speeds, a far cry from optimum. After the 70’s oil embargo, fuel economy became more important, leading to the initial CAFE (Corporate Average Fuel Economy) regulations. To help meet them, 6-speed transmissions began arriving and included other features such as a torque converter lockup clutch, overdrive, and electronic controls, all contributing to fuel economy gains.
In the late 90’s as fuel prices continued their steady rise and California’s emissions regulations became more stringent, transmission electrification began with the Toyota Prius electric hybrid. The primary feature of electric hybrids is the addition of motors inside the transmission which connect to various gearing elements. The motors effectively act to provide more transmission ranges, allowing the engine to run more efficiently, significantly improving fuel economy. The motors are powered by a battery pack kept charged by the engine and a home charger if a plug-in variety. In addition, during vehicle braking, the motors become generators, charging the battery as well as improving brake life. Analogous to mechanical ranges, having more electric speeds improves efficiency by enabling the motors to operate in their efficient zones. The Prius has just one electric speed, but other manufacturers had designs with more.
When the Prius was introduced, I was at Allison Transmission, then GM’s lead division for transmission electrification. Allison designs and produces transmissions for all manner of vehicles larger than passenger cars. Initially, electrification focused on the transit bus market and in 2003 production began on a 2-speed electric hybrid still produced for buses today. With its success, the architecture was downsized for SUVs and pickup applications. When combined with engine and other vehicle improvements, it provided significant fuel economy gains. It went into limited production in 2008 just as GM was forced to sell many of their assets including Allison, but unable to escape bankruptcy.
Soon after, I began work on a 4-speed hybrid being developed for even better fuel economy than the 2-speed version to help meet the 2012 revised CAFE standards. It was intended to complement a new series of 8 speed conventional transmissions concurrently being designed for rear wheel drive vehicles which started production in 2013. But vehicle fuel economy improvements kept coming, everything from vehicle electrification like the Volt to continued conventional powertrain improvements, including a joint venture with Ford on a series of 9-speed front wheel drive and 10-speed rear wheel drive transmissions. The standards could now be met without the 4-speed hybrid and it was eliminated, one indication the regulations can be met without an abundance of higher initial cost electrification. Further indications came from a detailed analysis by the regulating agencies who concluded the same thing–manufacturers across the industry can meet the standards even with low electric and hybrid penetration.
Since the revised standards, fuel economy innovations have blossomed with a range of offerings on every type of vehicle. Electric components have become affordable for many and the continued development of fuel cells adds yet another dimension. Continuously variable transmissions (CVTs) which mimic electric hybrids without adding motors are available in some vehicles. Dual clutch transmissions (DCTs) which combine the higher efficiencies of manual transmissions with the drivability of automatics are also gaining acceptance. Continued improvements to conventional drivetrains keep them viable as well.
The fact is automakers can continue to improve, and they’re putting technology to work to meet today’s federal standards. Vehicle sales have set records and the auto industry is employing workers in record numbers, in part due to these higher fuel economy features. Automakers are well positioned to meet standards and consumers can take full advantage of the lower fuel costs and reduced emissions that result. We’re moving forward—and it would be a mistake to slam on the brakes now.
Greg Kempf recently retired as a mechanical engineer from General Motors after 37 years. His career was mainly spent designing automatic and electric-hybrid transmissions for which he holds 15 patents. He’s now an aspiring writer, working on his first novel about climate change.
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