As the world of electric vehicles hangs on news of a Tesla battery update, the Californian electric car maker has taken time out to explain how it has cracked the 400 mile barrier with its Tesla Model S.
On Monday (US time), Tesla was finally able to officially confirm that the Model S has been rated for 402 miles (647km) by the US-based Environmental Protection Agency (EPA).
It’s a significant jump – 20% to be exact – in driving range from Tesla’s 2019 Model S 100D sporting the same battery pack design (previous incarnations of the premium electric sedan were known by the size of the battery pack and either “D” for dual motor or “P” for the performance variant).
It’s not exactly new news however, at least according to Tesla CEO and co-founder Elon Musk, who at the company’s first quarter 2020 earnings call said the range of the Model S had already reached 400 miles, but that the EPA had rated it for less allegedly because prior to testing a door was left open and 2% of range was lost overnight.
“As soon as the EPA reopens for testing, we will redo the test, and we’re actually confident that we will achieve a 400 mile or greater range with the Model S,” said Musk in April.
“But to be clear, the Model S, for the past two months — the true range of the Model S for the past two months has been 400 miles.”
Whether or not this was indeed the case (the EPA denied Musk’s claim), Tesla has now come through with the long-awaited 400 mile range.
This is important for two reasons: it shows that electric vehicles can be made to achieve a long driving range matching that of fossil-fuelled vehicles, and also showcases Tesla’s obsession with continuous improvement of energy efficiency.
We’ll take a moment here to clarify that EPA rated range is considered far closer to “real world driving range” (unlike NEDC which is still used in Australia and far exceeds how far an electric car can be driven under real world conditions – hence being referred to as standing for “not even damn close”).
How has Tesla done it? According to Tesla, as outlined in a blog post on Monday, it comes down to four factors: Significant mass reduction, new aero wheels and tyres, better drive unit efficiency and optimised recuperation of energy while braking.
Significant mass reduction
It’s a no-brainer that the lighter a vehicle is, the less energy will be needed to power its momentum.
While the Model S was Tesla’s first volume production vehicle, it says it has taken learnings from the design and manufacture of its Model 3 and Model Y.
This includes reducing mass in area not previously considered for the Model S (and presumably also the Model X).
Although Tesla does not elaborate in what new areas it has achieved this, it does add standardising seat manufacture has been a factor but also that it is using lighter weight materials used in its battery pack and drive units.
New aero wheels and tyres
New 8.5″ aero wheels dubbed “Tempest” are now included as standard on the Model S, allowing the vehicle less drag than previous wheels available on the Model S Long Range.
When coupled with a new custom tyre that Tesla says has been “specifically engineered to reduce rolling resistance”, a further 2% increase in driving range is possible says Tesla.
Note that as of Wednesday, the Tempest wheels are not available in Australia – we have contacted Tesla to confirm if this will be available to Australian customers.
Increased drive unit efficiency
Tesla says it has also made improvement in the efficiency of the Model S rear AC drive unit, by replacing the mechanical oil pump with an electric pump that “optimises lubrication independent of vehicle speed to reduce friction”.
Additionally, Tesla says that another 2% increase in driving range was achieved by improvement to the front permanent magnet synchronous reluctance motors that it shares with the Model 3 and Model Y.
Maximised regenerative braking
The “hold” mode that Tesla introduced in late 2019 has also been instrumental in achieving the new official driving range. Hold mode activates regenerative braking when the foot is off the accelerator pedal – a method of driving known as “one pedal driving”.
As Tesla explained at the time: “When HOLD is selected, your vehicle continues to use regenerative braking after decelerating to a low speed, and applies Vehicle Hold after coming to a complete stop. The HOLD setting maximizes range and reduces brake wear by continuing to provide regenerative breaking at speeds lower than approximately 5mph (8 km/h).”
Note that Tesla has not updated the range of the Model S on the Australian website as the new official EPA range rating does not affect the NEDC rating, and that the full real world range increase may be dependent on whether the Tempest aero wheels will be made available in Australia.
However, a price reduction for both the Model S and Model X applied in the US was also applied in Australia in late May. The Model S in Australia is currently priced from $124,900, and the Model X is currently priced from $138,900, both before government charges and on road costs.
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Bridie Schmidt is lead reporter for The Driven, sister site of Renew Economy. She specialises in writing about new technology and has been writing about electric vehicles for two years. She has a keen interest in the role that zero emissions transport has to play in sustainability and is co-organiser of the Northern Rivers Electric Vehicle Forum.