Range Finder: We stage a battery battle between Tesla and Taycan

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Editor’s note: With battery-powered electric vehicles becoming ever more common and competitive, it is time Driving turns its analysis to the performance metrics that matter most to EV owners — range. As with everything in the auto industry, it’s important to separate braggadocio from reality and, as with gasoline-fueled vehicles, there is often a great deal of variance between real-world energy consumption and the ratings offered by the EPA and Natural Resources Canada.

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The goal of our new Range Finder column, therefore, will be to test the range of electric vehicles under real-world conditions and report the actual — rather than advertised — distance they can travel before the batteries run flat. Our methods may be comparatively crude but we will be comparing cars over the same section of road at the same speeds and, often, as is the case with this test, in direct comparison with competitors.

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Range Finder: We stage a battery battle between Tesla and Taycan Back to video

One final note: At least for the time being, all testing will be done on major highways at typical highway speeds where range matters most. Extremely rare are EV owners who exceed the range capabilities of their battery in city driving.

No one dominates any automotive segment like Tesla lords over electric vehicles. More than half all BEVs, regardless of price, sold in Canada come from the Silicon Valley upstart, its dominance of the fledgling EV market so dramatic that TSLA’s market cap exceeds that of the top three legacy automakers — Toyota, Volkswagen and Renault–Nissan–Mitsubishi — combined. And, while much of its success can be attributed to its cars’ stylish exteriors, “ludicrous” performance and ground-breaking software, the one attribute that owners and media alike continually stress as proof of Tesla’s technological superiority is range. Indeed, it has become a given to attribute Tesla with a significant, nay unassailable, advantage in battery efficiency.

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But is that superiority real? To test that notion, Driving took a 2019 Tesla Model S 100D (the newest model available to us) and its most ardent challenger, Porsche’s 4S version of the Taycan, and put the two ultra-luxurious EVs through two thorough battery-draining tests, first along Ontario’s Highway 407 and then again, just to verify our result, along the 417/20 route between Montreal and our nation’s capital.

On paper, this should not even be a contest. Transport Canada rates the standard (i.e., not the Long Range) 100D at 539 kilometres of range while the EPA says the Taycan is good for but 327 km. That difference, 212 km, were it to translate into the real world, would represent a huge advantage, an added two hours on the highway before having to stop for a jolt of (electrified) java. On a more personal note, it would mean that, in a Tesla, I might be able to (barely) squeak out a run from my home in North York to my son’s home in the west end of Montreal on a single charge whereas, if the EPA’s numbers be true, in the Porsche, I’d need to stop somewhere before Brockville for a (not-so-)quick dine and dash. It is, to listen to the braggadocio on Tesla forums, the reason they buy Model S’s.

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But is it real?

Before we can definitively answer that question, unfortunately, we need to delve into a few anomalies specific to electric vehicles. Unlike fossil-fueled vehicles which can — and, as pretty much all of us can attest, often do — run until they are devoid of any fuel, EVs are designed to always hold some of their “juice” in reserve. That’s because a lithium-ion battery run to ground often turns into a brick (geekspeak for “gets permanently damaged”). Ditto, though to a less immediate effect, for a battery charged to the absolute brim. Almost all manufacturers, therefore, limit how “full” they will let their battery cells get when charging and how “empty” they will allow it to be discharged before shutting down in an act of electrical self-preservation.

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Depending on the manufacturer, as much as 10 per cent of their battery’s nominal charge is always held in reserve. For instance, a manufacturer might boast their latest super EV has a 100 kilowatt-hour battery when, in fact, only 90 kWh are usable. In fact, the Taycan 4S tested here boasts 93.4 kWh of lithium ions in its advertising, yet only 83.7 kWh are actually accessible to you. The Porsche, again in an act of self-preservation, will always keep 9.7 kWh in reserve. Ditto for Nissan’s Leaf, which has access to 56 of the battery’s rated 62 kWh; and Ford’s new Mustang Mach-E, which takes a even more conservative approach, only allowing 88 of its 98.7 kWh to be used.

And that’s where, like so many things involving Tesla, the plot thickens. For one thing, the exact amount of “usable” battery seems to be a constantly moving target. Tesla gives owners access to a greater percentage of its kilowatt-hours than those conservative legacy automakers. Exactly how much of its battery the driver has access to is, again, open to some speculation, but if the blogosphere is to be believed — and yes, I know how ridiculous that statement sounds — Tesla’s buffer could be as little as four kilowatt-hours, less than half what other automakers provide. Hell, even the actual size of the battery is open to some dispute. Serial battery hacker Jason Hughes, for instance, contends that some Model S’s are actually capable of as much 102.5 kWh, not the 100 kWh claimed, again with just a 4.0-kWh buffer.

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To put that all into a perspective more of us can understand, it’s kinda hard to calculate exactly how many litres per 100 kilometres your ICE is consuming when you don’t know how much gas the tank actually holds. Or, more accurately, how much of the gas in the tank the engine is allowed to burn. In other words, like so many things Elon Musk, what should be a single, straightforward objective calculation of efficiency — measured in EVs as kWh/100 km instead of the more common, for ICEs, L/100 km — turns out to be far more subjective.

What we do know is that after a full evening spent plugged in and both battery readouts indicating an almost equal state of charge, our 2019 100D promised 491 kilometres of electrically-powered zero emission motoring while the Porsche’s said the Taycan would only be able to manage 345 km. Advantage Tesla, right? Huge advantage, in fact, just like the brochure claims.

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The only problem is that three (and a little bit hours) later, they were both all but out of Lithium ions and, while the Porsche had almost exactly delivered its expected range — 342 km according to our calculations, versus its original 345-km claim — the Model S was all but as dead as a door-nail at 355 klicks. For the record, the Tesla underperformed its predicted range by some 136 kilometres, or negative 27 per cent, while the Taycan exceeded its EPA rating by 15 klicks (more than four per cent).

Whatever way you measure it, in real-world driving the Model S had a 13-kilometre range advantage, a far cry from the 146 kilometres it boasted before we started our test. Oh, and before all you Tesla owners start pillorying me as an outlier, I’m not the only one noticing a huge discrepancy between claimed and recorded ranges. Car and Driver also found “the average Tesla we’ve tested has delivered real-world range 27-percent below its EPA range figures ,” the exact same discrepancy we found. Edmunds had similar results in its testing — it found the Taycan 4S actually had more range than the Performance edition of the Model S — as did our competitors over at the Old and Male .

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So, what gives, you ask?

Unlike fossil-fueled vehicles which can run until they are devoid of any fuel, EVs are designed to always hold some of their “juice” in reserve

Well, for one thing, it seems Porsche seems to have been deliberately underestimating its range — perhaps the spectre of Dieselgate still casts a shadow? —  the company raising the 2021 4S’s official range rating to 365 kilometres without any significant upgrade to battery or software. For another, once you’ve normalized for things like cold-weather performance — which seems to affect the Tesla slightly more — you’re left with two factors. The first is that we tested the two cars in normal, not laboratory, conditions; and a large amount of our driving was at the constant 125 kilometres an hour that seems to be the new Canadian norm on divided highways.

Indeed, one of the anomalies we discovered during our tests is that while the Tesla seems a little more efficient — as measured by the two cars’ kWh/100 km consumption — than the Taycan at an EPA-pleasing 100 kilometres an hour, it’s actually less efficient than the Porsche when cruising at a steady buck-twenty-five. Exactly why the Taycan seems to have an advantage at high speed is difficult to determine, but Porsche engineers do make much of the fact the windings in their motors provide less resistance. I’m not sure that accounts for the differences we saw — about a five-per-cent advantage at 125 km/h — and suspect the Taycan’s high-speed efficiency advantage has more to do with its two-speed gearbox keeping its rear electric motor spinning at lower revs. Whatever the case, the claim the Tesla is more efficient didn’t pass the smell test on our highway trial.

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That’s borne out in spades with the second issue I had with our Model S, which is the fiction that was the Tesla’s range readout. Simply put, while most other EV’s dashboard range readouts provide accurate estimations of the mileage left in the “tank” — the Porsche’s is obviously very accurate, and the Chevy Bolt’s is also spot on — Tesla’s seems to keep lying right until the battery is empty. Indeed, our 100D kept exaggerating how many klicks we had left almost to the end.

It appears that Tesla’s range-finder remains resolutely married to the efficiency promised — that original estimation of 491 km — no matter how much energy it’s actually consuming. In fact, the farther we drove, the greater the disparity between the range the Tesla was predicting was left versus the actual — the miles calculated from the amount of battery charge left multiplied by its consumption. The same calculations for the Taycan, by comparison, were always right on.

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In the end, what we found is that, for a highway driving at least, Tesla’s claim to superiority seem illusory. The 100D’s promised greater range, were it real, is most certainly a reason to shop Tesla over Porsche. The piffling 13-klick advantage we saw in our high-speed, 125-kilometre-an-hour testing? Not so much.

The Taycan delivered exactly what it promised; the Tesla did not.

This is, as I mentioned, but the first in our series of Range Finder columns. Expect more as we put the most significant of electrified vehicles through their paces, putting their claims of efficiency and range to the test in real-world conditions. Next up is Toyota’s RAV4 Prime plug-in hybrid, one of the most sought after cars of 2021. Stay tuned April 20 for Range Finder’s evaluation of its performance.

LISTEN: Who says you can’t go for long drives in short-range EVs?

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