Aaron Isenstadt and John German
One in a series of technical briefs highlighting important innovations and trends in transmissions, which, overall, are similar to efficiency benefits and cost projections made at the time the 2025 CAFE standards were finalized.
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In the technology analyses for the 2025 corporate average fuel economy (CAFE) and greenhouse gas standards, the U.S. Environmental Protection Agency and the National Highway Traffic and Safety Administration projected that 8-speed dual clutch transmissions (DCTs) and 8-speed automatic transmissions (ATs) would dominate the 2025 fleet, completely replacing 6-speed DCTs and ATs, as well as continuously variable transmissions (CVTs) on non-hybrid vehicles.
Since the analyses were completed in 2012, the transmissions market has changed significantly. DCTs are entering the fleet at rates slower than expected, mostly due to consumer acceptance issues rather than technological setbacks. However, ATs and CVTs are filling the gap. New ATs have improved clutch design and more gear ratios, thereby exceeding projected efficiencies for ATs. Their growth in market share is strong, as the American market is very accustomed to the feel of a conventional automatic transmission. CVTs have recently solved some long-standing problems and are much more efficient, can handle higher torque, and cost less than they used to. CVT market penetration in new non-hybrid vehicles doubled from 9% in 2012 to 18% in 2015 and further growth is expected.
DCTs are still extremely efficient transmissions and OEMs and suppliers continue to improve their design to meet consumer acceptance challenges. Consequently, the transmissions market in 2025 will likely be split much more evenly among DCTs, ATs, and CVTs. The net effect will be that the average efficiency and average cost in 2025 will be similar to the rulemaking projections.
View the full series of working papers and technical briefs on passenger vehicle technology trends in the U.S. here.