Where Does Vehicle Efficiency Go From Here?

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In some ways, efficiency has been the main struggle in the automotive world for the last 40-50 years.

There have been times where reliability and overall quality struggled (for example, the Malaise Era for U.S. automakers), but during the last several decades vehicles have generally been pretty decent. It’s not uncommon at all for a car today to reach 200,000 miles, and 300,000 is becoming less and less unusual. Higher quality, tighter build tolerances, and electronic controls have driven past challenges in the automotive world largely away.

But, starting in the 1970s, efficiency and lowering pollution both became extremely important. For one, oil embargoes made customers care about efficiency. Subsequent gas shortages and price spikes have continued to happen from time to time and that keeps customers caring. Governments have also introduced pollution controls that pushed automakers further along the path to efficiency, while also challenging them to develop better engine technology.

After the Malaise Era, most automakers managed to deliver on better fuel economy and lower emissions while also delivering greater power. After adding electronic fuel injection, automakers moved from pushrods to overhead cams. Then, they moved to variable valve timing, multi-port injection, direct injection, reliable turbocharging, and lean-burn.

Things changed a lot when hybrid technology started to trickle into the scene. Engines could use the more efficient Atkinson cycle (as opposed to the common Otto cycle) when working in tandem with an electric motor, allowing for even greater efficiency. Now, the industry is moving away from combustion and into electric mostly because it’s far less wasteful of energy.

Now, the industry is working on increasingly efficient and compact electric motors, better battery technology, and even some very basic solar-powered vehicles. Better battery technologies have resulted in electric motors going into everything from bikes to scooters to motorcycles, too.

The Fight For Efficiency Isn’t Over

With zero emissions, it’s tempting to think that the hunt for efficiency is over. But, I don’t thing that’s true at all. Efficiency means a cheaper vehicle (fewer batteries needed), longer range, and lower overall environmental impacts. The most efficient electric vehicles don’t need the grid at all (it’s easy to charge an e-bike with a small solar panel), while the most efficient vehicles put less of a strain on both the grid and charging infrastructure.

Eventually, when battery supplies are plentiful, this won’t matter as much for pricing. Having a giant battery pack in a pickup truck won’t be an economic killer, in other words. But, all of those battery cells have to come from somewhere, and the environmental impacts won’t be much less than they are now. So, using less battery material will still be an important goal into the future.

The Limits Of Efficiency

At present, the most efficient electric vehicles on the market are on two wheels. Electric motorcycles get around 10 miles/kWh around town and 6-7 miles/kWh on the highway. You can’t get much lighter and smaller than a motorcycle, but the aerodynamics are terrible. Many EVs are starting to approach or do better than a 0.20 drag coefficient, while a motorcycle and its rider are between .50 and 1.0. What keeps them from being less efficient than cars isn’t the coefficient as much as the small overall size (to determine total drag, you multiply the drag coefficient by the frontal area, and motorcycles don’t have much of a frontal area.

So, getting less drag requires one of two things: lower speeds or low-drag designs around the size of a motorcycle.

The lower speeds are covered quite well by things like e-bikes, mopeds, some motorcycle-like scooters. These vehicles will continue to improve, but the energy needed to move them couldn’t get much lower.

For higher speeds, the vehicles need to be as slippery as possible and have the smallest frontal area possible. Three-wheeled cars like the upcoming Aptera are a good example of this, but other designs like the Electrameccanica Solo (discontinued earlier this year) manage to rival motorcycle efficiency without the downsides (open to the elements, motorcycle licensing, etc).

In some countries, a combination of these two things exists. Low-speed micro-cars allow for even better efficiency because they’re low drag while also being mostly operated at low speeds. But, these sorts of vehicles are only suitable for local driving in most cases.

The absolute bleeding edge of vehicle efficiency can be seen in experimental university project cars, which are optimized in even greater ways than the Aptera. As this video explains, not only does this make Aptera’s claims look a lot less speculative, but it shows that there’s still more efficiency to be eked out of vehicle designs.

The Other Option Nobody Likes: Mass Transport

The problem with cars like the Solo and Aptera is that they’re small. If you want to move a large family around at more than 20-30 miles per hour, you’re stuck with larger vehicles with bigger batteries to fit everybody and their things inside. But, if there’s an even bigger vehicle that can hold your family and a bunch of other families, it’s possible to get the per-person energy needed back down to micromobility levels.

Personally, I’m not a big fan of forcing this on people. The desire for control over one’s own movements combined with the low quality and availability of transit in many places makes it a not too viable option. So, the challenge in this case isn’t as much efficiency as quality. To get people to actually want to use transit, it needs to be clean, free of crime, widely available, and with frequent departure times. It also needs to be minimally invasive (no security theater, searches, or prohibitions on the carry of personal items).

But, there’s no reason that a healthy transportation system can’t have a mix of the best modes to keep it efficient. Buses and trains don’t need to go down every street if it’s safe to ride a scooter or bike to the station for longer hauls. Cars can be part of a safe mix of all modes by using tiered route types (highways, roads, and streets instead of “stroads”).

An “all of the above” approach is probably the best way to keep pursuing efficiency long into the future.

Featured image by Jennifer Sensiba.