10 Ways Internal Combustion Vehicles Are Getting Cleaner And Greener

According to government and industry sources, the time-honored internal combustion engine (ICE) could be honored with much more time – as in indefinitely.

While electrification enthusiasts have predicted a pending demise for the ICE, the U.S. Energy Information Agency predicts in 2035 that 99 percent of light-duty and heavy duty vehicles, particularly in commercial use, will still rely on fuel-burning engines.

To keep fossil tech evolving for commercial and passenger vehicles, innovations are being rolled out to squeak incremental gains, while research is ongoing to increase their future capabilities.

“Improving the efficiency of internal combustion engines is one of the most promising and cost-effective near- to mid-term approaches to increasing highway vehicles’ fuel economy,” says the U.S. Department of Energy’s Energy.gov website. Lab tests, it adds, have shown fuel economy can be improved by more than 50 percent and even possibly 75 percent over today’s engines.

2014 Corvette LT1 small block V8 has gasoline direct injection, cylinder deactivation, variable valve timing.

2014 Corvette LT1 small block V8 has gasoline direct injection, cylinder deactivation, variable valve timing.

While we often hear of the government giving a plug for plug-ins, its playing all angles should not come as a surprise, even to electrification enthusiasts. Presently 99 percent of America’s 16.5-million annual passenger vehicle market still relies on the ICE – not to mention hybrids and plug-in hybrids which themselves use internal combustion engines.

But with next-generation lithium-ion batteries on the horizon for electrified passenger vehicles, and anything possible after that, it does remain to be seen how things actually unfold. Really, it’s a technological shakeout we’re in – with the entrenched ICE being tenaciously held onto, and those invested in it not relinquishing their grip willingly, nor are they being forced to.

On the contrary, federal Corporate Average Fuel Economy (CAFE) rules demanding “54.5” mpg – low 40s on the window sticker – by 2025 are pushing automakers toward electrification, but give them a way out, if they desire. The rules actually have been written so that a mere 1-3 percent of vehicles must resort to plug-in electrification, although more is encouraged.

There are 253 million cars and trucks on American roads today, and according to Energy.gov, nearly 60 percent of total U.S. oil consumption and more than a quarter of the country’s greenhouse gas emissions comes from on-road vehicles.

Want to know why Tesla has fans? One reason is it's the only automaker that utterly rejects internal combustion while threatening to "disrupt" or throw a monkey wrench into the existing paradigm.

Want to know why Tesla has fans? One reason is it’s the only automaker that utterly rejects internal combustion while threatening to “disrupt” or throw a monkey wrench into the existing paradigm.

Armchair pundits often suggest we should just cut through the Gordian knot with known plug-in technologies, but industry is heavily invested in the present paradigm, and wheels are turning slower than some who think like Elon Musk would desire.

With your taxpayer dollars behind them, the federal government is promoting an “all of the above” strategy that gives a leg up not just to plug-in battery tech, but also hydrogen fuel cells, alternative fuels, and the internal combustion engine.

Cummins-Peterbilt ‘SuperTruck’ Posts Benchmark 10.7 mpg

According to the University of Michigan Transportation Research Institute, since October 2007 average window sticker fuel economy values on new cars sold in the U.S. have gone up only 5.3 mpg to 25.4 mpg as of June. This is true despite major automakers having had production-ready tech for 50-100-plus-mpg vehicles all along.

Like it or not, this is what we have in a world of politics, compromise, entrenched interests, and following are ways the ICE is maintaining its foothold in the western world.

Production Technologies

Automakers have an arsenal of technological choices enabling them to stay ahead of CAFE, California rules, and various global regulations dictating average across-the-board fleet mpg and CO2 improve year by year.

Advanced Engine Technologies

According to the U.S. Department of Energy, engine technologies stand to improve efficiency and save operational costs over vehicles’ lifetime. Federal efficiency and cost-saving estimates below are based on DoE assumptions of 166,000 lifetime miles, fuel priced at $2.81, and compared to an average 22 mpg vehicle.

1. Forced Induction

In simplest terms, supercharging and turbocharging are two means to compress more air and thereby more fuel into a combustion chamber.

Supercharged Volkswagen/Audi engine.

Supercharged Volkswagen/Audi engine.

Some fighter planes in World War II used forced induction, and the tech had been around before that, but it’s a finding computer-aided resurgence these days with the trend to downsize engines and cram more fuel and air in.

This gives smaller engines the power of larger engines while allowing automakers to submit them to relatively tame and legal drive cycles that may report remarkable mpg and CO2 scores.

Forced induction is an expedient way to serve up an engine that can offer satisfying power with better efficiency – just so long as the driver does not push the gas to the floor, at which point the maxim “your mileage may vary” comes back in full force.

Efficiency improvement potential: 2-6 percent
Lifetime cost savings: $400 – 1,300

2. Cylinder Deactivation

Vehicles are increasingly seeing this computer-enabled trick employed that can make an eight-cylinder run on four cylinders, or a six-cylinder run on three cylinders under light load use, such as on the highway.


The technology can also be called “multiple displacement,” or “displacement on demand,” “active fuel management,” or “variable cylinder management.”

It really is a decent concept too, as even, for example, a 450-horsepower Chevy Corvette C7 has been reported as returning over 30 mpg on a tame highway cruise which is amazing compared to what used to be expected.

Efficiency improvement potential: 4-10 percent
Lifetime cost savings: $800 – $2,100

3. Gasoline Direct Injection

With this technology, fuel is injected directly into the intake port and mixed with air as the air-fuel mixture is drawn into the cylinder.


Also known as “direct fuel injection,” and “spark ignition direct injection (SIDI)” the setup makes the fuel-air mixture a bit cooler enabling higher a compression ratio and increased combustion efficiency.

This means higher performance and less fuel consumption.

Efficiency improvement potential: 2-3 percent
Lifetime cost savings: $400 – $600

4. Variable-Valve Timing and Lift (VVTL)

Intake valves control fresh air into the cylinders and exhaust valves control the flow of exhaust out of the cylinders.


When and how long the intake and exhaust valves open (timing) and how much the valves move (lift) both affect engine efficiency.

VVTL automatically optimizes valve timing and lift for varying engine speed and power.

It contrasts with traditional fixed valve timing and lift settings, which compromise efficiency between high and low engine speeds.

This tech includes “variable valve actuation,” “variable-cam timing,” “cam phasing,” “variable valve timing and lift electronic control (VTEC, VANOS, VVT-i),” etc.

Efficiency improvement potential: 1-11 percent
Lifetime cost savings: $200 – $2,300

5. Stop-Start Systems

Anyone who knows about hybrids knows what Stop-Start tech is given it is universally used in hybrids and plug-in hybrids.


In short, Stop-Start automatically turns off the engine when the vehicle comes to a stop and restarts the engine instantly when the brake is released or the accelerator is pressed.

SEE ALSO: Stop-Start Technology Found On Half Of Vehicles By 2021

It’s a simple concept that prevents fuel from wasting at idle.

Automakers may also borrow another technology from hybrids – regenerative braking – to augment the system and convert mechanical energy lost in braking into electricity, which is stored in a battery and used to power the automatic starter.

So-called “micro hybrids” can see these systems in play. Unlike a true hybrid, electrical energy stored is not used to power a traction motor. Higher voltage batteries in addition to the 12-volt system take the converted mechanical energy and can power subsystems like the HVAC, infotainment, etc.

Efficiency improvement potential: 2-4 percent
Lifetime cost savings: $400 – $800

Advanced Transmission Technologies

Another area to save energy is by optimizing how the engine’s power is routed. New transmissions are being paired to gas and diesel engines to raise the bar as feasible.

6. Additional-Gear Automatic Transmissions

We’ve already seen automakers such as Chrysler, Hyundai, Ford, and Volkswagen, among others, announcing or rolling out automatic transmissions with 10 gears.


Every gear above a traditional four-speed auto does help keep the engine at an optimal operating range thus improving potential efficiency.

The Energy Department says efficiency improvements are on average as follows: 5 gears – 2-3 percent; 6 gears – 3-5 percent. 7 gears – 5-7 percent; 8 gears – 6-8 percent.

And on it goes. Adding gears helps companies avoid electrification as incremental gains added to other tech improves conventional vehicles enough to stay ahead of the regulations.

Efficiency improvement potential: 2-8 percent
Lifetime cost savings: $400 – $1,700

7. Continuously Variable Transmission (CVT)

Here’s another technology more widely associated with hybrids finding its way into conventional vehicles.


CVTs use a pair of variable-diameter pulleys connected by a belt or chain instead of gears and they can produce an infinite number of engine/wheel speed ratios.

Advantages include no interruption of power during gear changes, seamless operation, no downshifting or hunting gears on hills or when passing, and better fuel efficiency.

Efficiency improvement potential: 1-7 percent
Lifetime cost savings: $200 – $1,500

8. Dual Clutch Transmission (DCT)

Also called “Automated Manual Transmissions,” DCTs combine the benefits of manual and automatic transmissions.


Manuals are lighter with less energy loss but are not as convenient as an automatic.

DCTs don’t require manual use of a clutch for shifting and may be manually operated by a lever or paddles on the steering column, or they will operate automatically.

This is electronically controlled (shift-by-wire) setup, with shifts performed hydraulically or by electric motor.

High performance cars and race cars have gone this way although purists (or traditionalists) may still cry for the manual stick.

Efficiency improvement potential: 7-10 percent
Lifetime cost savings: $1,500 – $2,100

More Advances

Following are a couple other miscellaneous efficiency helpers.

9. “Light-Weighting”

Lotus pioneer Colin Chapman was famous for saying “Simplify, then add lightness” as a formula for creating high-performance, nimble cars, but lighter weight pays dividends when the goal is fuel economy.


Lighter vehicles require less energy to propel them, and automakers are always keen to do this without compromising other design goals.

Common ways include use of high-tensile steel, aluminum, other lightweight materials including carbon fiber, and decreasing the powertrain size.

At the same time, vehicles must meet stringent and increasing safety standards, which takes material – strategically placed – along with technologies that all add to the weight.

You might say today many are complicating and trying to add lightness, but other efficiencies make up for the effort so that most agree today’s vehicles are better than ones from the good old days. (At least most people think so).

Efficiency improvement potential: 3-4 percent per 5-percent reduction in weight
Lifetime cost savings: $600 – $800

10. Low Rolling Resistance Tires

Tires are incredibly important as they are your only point of contact with the road, but they also create varying degrees of friction.


Another trick borrowed from hybrids and electric cars are LRR compounds that today are better than earlier less-grippy rubber that sacrified too much control for an incremental decrease in rolling resistance.

The idea is conservation of energy and it does work though it is a compromise still. High-performance cars do not get LRR rubber because it cannot give as high a lateral acceleration and adhesion characteristics. More often ordinary cars get them, for yet-more efficiency gains.

Efficiency improvement potential: 1-3 percent
Lifetime cost savings: $200 – $600

More To Come

Our list hits the high spots, but is not comprehensive.

What’s more, the U.S. Department of Energy’s Vehicle Technologies Office continues forging ahead on ICE tech, applicable to passenger vehicles, and commercial vehicles like tractor trailers which account for 4 percent of vehicles on the road but slurp 20 percent of the fuel.

Along with hybridization – which is by extension an ICE-complementing technology – myriad technologies are being researched and developed for tomorrow’s vehicles including ones you may be able to buy.

SEE ALSO: Is a 200-Mile EV the Next Automotive Benchmark?

Included in future ICE tech is recovering energy from engine waste heat, superior low-friction lubricants, advanced combustion technologies, alternative fuels, and more.

The world is not ready to give up the ICE unless it is somehow forced to.

What About Electrification?

In two years we may have 200-250-mile EVs costing in the mid 30s and battery researchers are pushing for “beyond lithium-ion” with many scientists wanting to be the one who discovers a true “game changer” that can seriously threaten to put the ICE on ice.

Chevy Bolt (shown), Tesla Model 3, and the next Nissan Leaf promise 200 to possibly 250 miles range. They are the next benchmark, to be priced in the mid 30s.

Chevy Bolt (shown), Tesla Model 3, and the next Nissan Leaf promise 200 to possibly 250 miles range. They are the next benchmark, to be priced in the mid 30s.

That’s the goal, but no one really knows the future even if many are willing to forecast on its behalf. And certainly the will is there, and reasons for positive conjecture.

In the mean time powers that be are trying to extend the relevance of internal combustion with lower emissions, higher efficiency and until a technology is embraced to unequivocally challenge the ICE, this is the plan until further notice.