Governments across the globe and segments of the automotive industry alike are tolling the bell for internal combustion engines. Norway, France, the United Kingdom, India, and the Netherlands all plan to ban the sale of internal combustion vehicles as soon as 2025. China and Germany seek to enact a similar ban, though neither has a time frame in mind, and the state of California is evaluating the idea. Should battery-powered cars live up to the promises made by Tesla's Elon Musk in November, when he revealed the potentially game-changing electric semi truck and revived Roadster, the timeline on which these countries hope to bar the sale of new internal combustion vehicles could indeed be realistic.
Key industry players, such as General Motors, Continental, and Honda, believe electricity to be the propulsion method of the (near) future, whereas others like Mazda and Lamborghini, think that internal combustion will remain viable for some time. The former does not yet see electric vehicle technology—or its supporting infrastructure—as superior to that of the established internal combustion market, and the latter promises to keep a naturally-aspirated V12 engine as the centerpiece of its flagship model.
As conservative as Lamborghini has become, it admits that electrification could partner its V12 engines in forthcoming models, and despite resisting the integration of forced induction, the new Urus crossover will be the first Lamborghini to leave the factory with turbochargers. With the improvements made to batteries over the last few decades, and the improved power density and fuel efficiency available from forced induction engines, it is hard to argue the bull-badged brand's submission to the forward march of transportation technology.
I stand with Mazda and Lamborghini in the belief that the market for internal combustion will not evaporate once convenient, mass-produced electric vehicles are present in all market segments. Like other forms of outmoded transportation, such as horses, trains, and civilian aviation, enthusiasts for the old-timey will remain. Members of the automotive community, such as Jay Leno, already bother with keeping quaint, obsolete automobiles on the road. Be it steam, turbine, or airplane-powered, there will always be interest in antiquities because of the unique experiences they offer.
Provided electricity is the future of cars, I expect the self-driving car market to select it as the primary form of propulsion over internal combustion, which could survive as the first choice for niche markets, like small-production sports cars. Odds are, however, the days of naturally-aspirated, high-displacement engines without electric assist are nearing an end. That old adage about replacement for displacement was disproven decades ago when mass-produced cars started to see forced induction engines fitted as standard.
With the downward trend of engine sizes since the western world realized oil was not an endless resource and the limited size of future markets for petroleum-burning vehicles, we can expect engine displacement to shrink further to decrease both fuel consumption and the cost of designing and producing new engines. This comes at the price of reduced torque, meaning chassis weight has to come down too. The genius behind the McLaren F1, Gordon Murray, has a solution to this problem—iStream.
iStream is a manufacturing system devised to slash the cost and time to produce carbon fiber chassis, like those used in motorsport and modern supercars. Carbon fiber's minimal weight and high rigidity make it the ideal material for many applications, but the necessity of an expensive industrial autoclave restricts it to small-scale production. It is estimated that iStream permits an approximate weight savings of close to 20 percent, which would allow a car like the Mazda MX-5 to undercut a one-ton curb weight, were it built with this process. The apparent lower setup investment and smaller environmental impact are but icing on the cake.
Combustion-powered cars of the future still need some form of low-end torque that reduced weight cannot entirely compensate for, and the answer to that problem is found in performance-focused hybridization techniques already employed on modern hypercars. The McLaren P1 already uses an electric boost to fill the gaps in the power band with a surge of electric torque sourced from a battery charged via the magic that is regenerative braking.
Look to Continental for an idea on how existing regenerative systems can be improved. Back in August, the company released its regenerative braking concept, built on the principles of current systems, but utilizing novel design and materials to improve efficiency, performance, durability, and ease of service. It boils the rotating assembly down to but a handful of simplified parts, permitting some to be made from lightweight aluminum, rather than steel or cast iron, reducing weight by an average of 4.4 pounds per corner. While that may sound marginal, reducing unsprung weight has a far greater effect on efficiency and performance than sprung weight does. The increased reliance on thrifty regenerative braking rather than wasteful friction braking would decrease part wear, and further increase efficiency.
The electric boost would not serve as the sole purpose for the juice harvested by regenerative braking systems, though—it could be used to recharge the car's main battery in the future, some of which could jump up from the modern standard of 12 volts to the neighborhood of 48 volts, like the one Mercedes is trialling on the 2018 S-Class sedan. This is enough juice to run most of an engine's accessories, such as the air conditioning and fluid pumps, without the use of an efficiency-sapping belt or chain, and it irons out some of the issues with idling and start-stop.
It also serves up enough current to provide a boost for the engine via an electric supercharger, one which cooperates with a turbocharger in a forced induction system known as twincharging. Twincharging was long neglected by car companies, due to its complexity, and the advent of almost lag-free twin-scroll and variable geometry turbochargers. Mercedes is not the only company looking to bring such systems to the mass market; Mazda and General Motors are each evaluating their own twincharging designs, albeit with differing designs.
Mazda's concept, revealed in a patent filing with the United States Patent and Trademark Office, uses an electric supercharger like that of Mercedes' engine, but in addition, it uses a pair of turbochargers, rather than Mercedes' single unit. Instant, efficient boost would be available from the supercharger, but it could be deactivated the moment the first (or both) of the turbochargers reach operating speed.
General Motors' twincharging design patent reveals that the American brand, instead of pursuing an electric supercharger, has stuck with a mechanical, belt-driven design. Rather than a static belt ratio, GM's supercharger is shown to be driven by a continuously variable transmission (CVT) mechanism, with an electronic controller to vary supercharger speed by adjusting CVT pulley ratios. GM's patent, however, extends to other parts of the engine's induction system, such as the intake valve.
Current camshafts use an avocado-shaped lobe to actuate valves in the cylinder head, though a disadvantage of this system is that valves spend much of their time partially open, reducing efficiency. GM offers two redesigns to correct this, which open the intake valve to its fullest sooner and close it faster. One squares off the cam lobe while another adds a second lobe as part of the follower and is activated by oil pressure. This increases the efficiency of the intake stroke, allowing for more air to rush into the cylinder, and thus, increasing power density.
Hyundai, too, wants in on the fun and is promising that a system under development, titled "continuously variable valve duration," will be one of the stepping stones on the path toward motorsport-quality engines for road cars. No information on how this system is intended to work has yet come forward, though.
Though older news, Koenigsegg's Freevalve system, a prototype pneumatic valve system, gives similar attention to the issue of valve control. GM adds but another way to handle the problem with its mechanical system.
There are further gains to be made once the air is in the cylinder, and fuel is injected. Infiniti is pioneering an engine with a variable compression ratio, which would allow the engine to switch between low boost and a high compression ratio for efficient cruising to high boost at a low compression ratio for quick acceleration. Systems for adjusting engine control on the fly depending upon load requirements already exist, such as cylinder deactivation, but variable compression takes the idea a step further, by widening the gap between economy and performance operation.
On the subject of compression, Mazda has more to add. Its Skyactiv-X engine, coming in the 2020 Mazda 3, is set to be the first commercial gasoline engine to utilize compression ignition. This type of ignition is the principle behind diesel engines and is what allows them to produce so much torque with great efficiency. As we know well by now, diesel engines suffer from worse emissions than gasoline engines do, so the promise of the gains available from a gasoline compression ignition engine has long been attractive. Mazda's Skyactiv-X still utilizes a spark plug, but only for better control of the ignition itself, allowing for compression ignition to occur under load conditions where it would otherwise be impossible with a gasoline engine.
Technologies like all of those described above will be requisite for automakers who seek to get the most out of internal combustion before its sale is curtailed over the next few decades. Hyundai thinks 50 percent thermal efficiency is achievable from mass-producible road car engines, a figure scarcely matched by Mercedes' Formula 1 program in a controlled environment after the investment of a decade and a half billion dollars, and a complex device known as an MGU-H that converts excess heat to electric current.
It is a fool's game to estimate what all of these technologies would accomplish if combined, but daydreaming about the car that would result is captivating. A featherweight iStream chassis, in which is mounted a downsized, rev-happy engine, equipped with advanced hybridization, lag-free forced induction, complete intake valve control, variable compression, compression ignition, and a 48 volt accessory system should be enough to make almost every driver who enjoys winding out an engine to the redline ready for the future.
Whether or not the roads of tomorrow are dominated by self-driving electric boxes won't matter, because as long as internal combustion has a future a fraction as bright as we, its proponents, think it can be, its place in the market could remain for those of us who would rather row gears.