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Tesla’s industry-leading efficiency stems from its vehicle design culture
Posted on October 05, 2019 by Charles Morris
More range! More range! That’s the mantra that has replaced the More Power! of the ICE era. How much range is enough? All we know at this point is that car buyers want more. Tesla, always attuned to consumer desires, upped the stakes once again in April, increasing the range of Model S to what Road & Track colorfully calls “a bladder-busting 370 miles.” The interesting thing is that the company achieved this 35-mile increase without increasing the size of the battery.
Above: Tesla's Model S (Photo: Casey Murphy, EVANNEX)
As Tesla explains, its engineers were able to boost range by making incremental improvements to several parts of the powertrain: “All Model S and X vehicles now benefit from Tesla’s latest generation of drive unit technology, which combines an optimized permanent magnet synchronous reluctance motor, silicon carbide power electronics, and improved lubrication, cooling, bearings, and gear designs to achieve greater than 93% efficiency. Pairing a permanent magnet motor in the front with an induction motor in the rear enables unparalleled range and performance at all times. The net effect is a more than 10% improvement in range, with efficiency improvements in both directions as energy flows out of the battery during acceleration and back into the battery through regenerative braking.”
More range is bound to make the appeal of Tesla’s world-leading electric vehicles even greater. However, the real story here is not about range, but efficiency. At the moment, EV designers are focused on maximizing range, but if at some point the market decides that there’s such a thing as “enough range,” designers could leverage greater efficiency in the powertrain to make battery packs smaller, giving their vehicles more space, better performance and/or lower prices. Efficiency also offers a direct benefit for consumers - it translates into lower electric bills.
Above: Tesla's Model X (Flickr: Alang7)
Tesla’s EVs are some of the most efficient on the market - to give one example, the Model S Performance full-size sedan is substantially more efficient than the tiny smart EQ fortwo. When it comes to the vaunted “Tesla killers” - Audi’s e-tron and Jaguar’s I-PACE, the larger Tesla Model X simply blows them away. As Road & Track explains in a recent article, Model X is so much more efficient that it offers 91 more miles of range than the Audi and 121 more than the Jag, even though the Tesla’s battery pack is only slightly larger.
As R&T sees it, the reason the legacy automakers’ latest and greatest EVs can’t match Tesla’s aging models comes down to inefficiency, not only in their powertrains, but in their corporate cultures. Tesla’s culture is one of continuous improvement - in the eight years that Model S has been on the market, its efficiency has increased by 25 percent, from 89 MPGe to 111. Tesla has improved the vehicle’s motors, air suspension, tires and even its wheel bearings.
Above: Tesla Model S charging (Flickr: Jakob Harter)
Another policy prized at Tesla is open communication between departments, in contrast to the “silos” that so many employees of traditional corporations complain of. As R&T explains, Tesla’s newer wheel bearings are more expensive than the old ones, but they may have added as much as 15 miles of range at far less cost than adding battery capacity. The newer Teslas also use Brembo monobloc brake calipers. “Because they can be made to retract the pads from the spinning rotors faster and more reliably than sliding calipers, monoblocs reduce friction - enough to provide up to 20 miles of increased range,” writes Road & Track’s Jason Cammisa. “The additional stopping power, credibility, and better pedal feel are just added bonuses.” Are the Brembos expensive? Very - but on a per-mile-of-range basis, they’re still cheaper than batteries, and Tesla figured that out because the brake team communicates with the battery engineers, and they cooperate to continuously improve the company’s vehicles.