Manufacturers Are Emphasizing Efficiency More Than Ever
So why is it that the latest cars from established manufacturers can’t come close to the efficiency of the Silicon Valley start-up’s aging models? It comes down to inefficiency, both in the cars and in the corporate culture. I should point out that the Model S has become better than 25 percent more efficient over its eight model years, climbing from 89 MPGe to 111. The latest upgrades include revisions to tires and air suspension, changing from an induction-type front motor to a more efficient permanent-magnet design, and revised wheel bearings.
Yes, even wheel bearings count. These have slightly less drag than the car’s already-efficient bearings. The new part is more expensive to manufacture, but Tesla’s engineering teams don’t speak just in terms of dollars, they talk of Battery Bucks—a measure of how much cost can be saved on batteries for every efficiency gain made.
The exchange rate between Battery Bucks and Bearing Dollars must be favorable, because the new bearings made it into production. Rather than shrink the battery, though, Tesla took advantage of the increased range: the new parts are responsible for up to an additional 15 miles compared with traditional bearings. Fifteen miles is more than a quarter of the range of that microscopic Smart Fortwo, and I bet those bearings cost much less than a fourth of the Fortwo’s battery.
Thinking in terms of Battery Bucks allows the company’s departments to work together, rather than in isolated silos as at traditional automakers. There, one imagines braking guys might fantasize about four-piston, monobloc calipers, but their budget would never allow that luxury. At Tesla, the brake guys looked at their Battery Bucks and realized that it cost less overall to use expensive Brembos. 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. The Brembos were easily paid for using Battery Bucks. The additional stopping power, credibility, and better pedal feel are just added bonuses.