What Does The Tesla Model X Tell Us About Fuel Efficiency?

The Tesla Model X is the first fully electric SUV in the world. It was announced with much fanfare — Bioweapon Defense Mode! Falcon-wing doors! Clown-car volumes of people and luggage coming out! — by Musk with a handful of lucky and rich people getting early editions and paying a big premium for the privilege. But something didn’t get as much attention.

It’s the first fully electric sport utility in the world and this ‘offroad’ crossover category is a good lens to look at fuel efficiency for average people. This category and minivans basically replaced family station wagons and full-sized sedans a couple of decades ago as primary family vehicles.

Let’s get something out of the way: the Tesla Model X is the most fuel efficient SUV ever by an extraordinary margin. 92 miles per gallon equivalency for combined (highway and city) mileage, per the US Department of Energy’s standardized model.

For fun, let’s look at the next competitors, hybrid gas-electric SUVs, and only the best of them. The Model X is basically 3 times more fuel efficient by this standardized approach than the absolute best of its competitors.

What about the much more common small gas and diesel SUVs? How does over 4 times better sound? Note that the Audi Q5 diesel at the bottom is one of the ones implicated in the recent VW scandal, so the numbers are highly suspect and likely to be impacted by fixes.

I won’t even bother to put the larger SUVs on display. It’s kind of shameful how bad they are.

But if you look at reality, the Model X — and other full electrics — are even better.

So, the Model X has 3 to 4 times the fuel efficiency of similar vehicles. But there are two challenges with this.

The first is that the measure of miles per gallon (including the related miles per gallon equivalency) itself is quite remarkably uninformative.

“Let’s say for numerical simplicity that you want to go 240 miles in both. In your initial situation, it takes 20 gallons for the truck and 8 gallons for the car, for 28 gallons total. If you replace the car, the same journey will take 6 gallons for the car for a total of 26 gallons. If you replace the truck, the new one takes only 15 gallons for a total of 23 gallons. It’s a much better deal to replace the truck, even though the MPG gain seemed less impressive. We would have had to replace the 30 MPG car with one that gets 80 MPG to achieve the same 23 gallon result. If we had been using GPM instead of MPG, we’d never get confused on this point, and would therefore make smarter decisions.“

The second is that it’s incredibly easy in most parts of the developed world to buy carbon- and pollution-free electricity at a tiny premium, which barely dents the cost savings of electricity vs gasoline. You can’t buy carbon- and pollution-free gasoline or diesel. It doesn’t exist outside of a handful of demonstration pieces and conversions. Most people who buy Teslas buy carbon- and pollution-free electricity as well, because they are sensible and can afford the slight premium.

The Model X wins using the brain-dead, dinosaur-oriented miles per gallon comparison, and is (literally) infinitely better when you look at what you can do with virtually no effort and no meaningful cost.

So, how should we be measuring vehicle efficiency?

Electric cars are required to have a fuel efficiency rating, but the one that’s used is a legacy of internal combustion vehicles. I expect in a few years more sensible measures will come into play which make it really clear how bad internal combustion vehicles are. Things like:

1. kWh/100 miles or kilometres
2. Cost of fuel per 100 km
3. Carbon emissions per 100 km
4. NOx emission per 100 km

In fact, let’s look at the numbers for the first couple of choices so that it can really sink in how big a deal this is.

These numbers aren’t mine but are from MPG for Electric Cars? and the costs are based on $0.10 per kWh and $3.50 per gallon of gasoline. Looking at the best of the hybrid SUVs, it costs close to 5 times as much to drive the same distance.

And that’s without factoring in the Supercharger network, which is an enormous game changer for travel which is mostly under appreciated for how disruptive it is:

“3100KM’s driven, 60 hours traveling, 16 superchargers visited, 5 family meals, $3.40 in electricity costs for the drive, 2 Motel Stays, 1 Mass attended and my family of six arrives at Disneyland to continue the adventure.”

That’s right. All of the fuel for the trip cost $3.40. The Lexus Hybrid would have cost about 60 times more for the trip. The Acura would have cost about 90 times more. When hundreds of dollars difference exists for a single trip, that becomes a factor in decision making. And the Supercharger network is shifting to become carbon-neutral even though grids are decarbonizing and in all but the filthiest grids today electric cars are already the clear winners per recent analyses.

When you start comparing apples to apples instead of the apples-to-basketballs comparison that is currently being foisted on the general public, then people will really start figuring out why smart people are going electric. You can bet the traditional car companies are investing heavily in lobbying to ensure that miles per gallon or litres per 100 km continue to be the defining measure.

It’s in traditional car companies’ best interests to keep people multiplying by the cost per gallon or litre instead of the cost per kWh.