Lably
Skip to content

History of plug-in hybrids

  • 38 min read
  • 18 chapters
BYD F3DM plug-in hybrid in Bilbao, Spain
Mariordo (Mario Roberto Duran Ortiz) · CC BY-SA 3.0

Related on Lably

Through Supply (economics), Iteration and Electric motor

Global sales of plug-in hybrids grew from over 300 units in 2010 to 222,000 in 2015 and 7.2 million in 2025. As of December 2025, China is the world's largest plug-in hybrid car market with a stock of 15 million units, followed by the United States with 1.9 million vehicles, Germany with 1.1 million, the UK with 860,000 and France with 810,000. As of December 2025, there are about 25 million plug-in hybrid electric cars in the world, about one third of the total stock of 75 million plug-in electric cars. In the half year to June 2025, the BYD Song Plus was the world's top selling plug-in hybrid car, with 188,500 units sold (5.4% of all PHEV sales) over the period. BYD models accounted for seven of the top ten best-selling PHEVs over this period, with the Li Auto L6 (96,400), Galaxy Starship 7 (70,900) and Aito M9 (58,700) also among the top ten.

1899–1999

Hybrid vehicles were produced beginning as early as 1899 by Lohner–Porsche. Early hybrids could be charged from an external source before operation. However, the term "plug-in hybrid" has come to mean a hybrid vehicle that can be charged from a standard electrical wall socket.

The July 1969 issue of Popular Science magazine featured an article on the General Motors XP-883 plug-in hybrid. The concept commuter vehicle housed six 12-volt lead–acid batteries in the trunk area and a transverse-mounted DC electric motor turning a front-wheel drive trans-axle. The gasoline-powered engine was connected to the trans-axle via a worm gear. The car could be plugged into a standard 110 Volt AC outlet for recharging.

In 1971, Dr. Andy Frank, the inventor of the modern PHEV, begins working on hybrids and PHEVs. He is professor of Mechanical and Aeronautical Engineering at the University of California at Davis.

The September 1975 issue of Popular Mechanics magazine featured a cover story on an experimental "turbo-electric" hybrid that "plugs in overnight for thrifty driving around town." Built by electronics engineer Harry Grepke, the vehicle used eight 12-volt truck batteries and a turbine genset. Grepke claimed an all-electric range of 50 miles (80 km).

In 1989, Audi produced its first iteration of the Audi Duo, a plug-in parallel hybrid based on the Audi 100 Avant Quattro. This car had a 12.6 bhp (9.4 kW) Siemens electric motor which drove the rear wheels. A trunk-mounted nickel-cadmium battery supplied energy to the motor that drove the rear wheels. The vehicle's front wheels were powered by a 2.3-litre five-cylinder engine with an output of 136 bhp (101 kW). The intent was to produce a vehicle which could operate on the engine in the country and electric mode in the city. Mode of operation could be selected by the driver. Just ten vehicles are believed to have been made; one drawback was that due to the extra weight of the electric drive, the vehicles were less efficient when running on their engines alone than standard Audi 100s with the same engine.

Beginning around 1990, Professor Andy Frank of the University of California, Davis began using student teams to build operational prototype Plug-in hybrid electric vehicles. His work attracted industry support and funding from Nissan, Koyo Seiko, General Motors, Saturn, Ford, Visteon, JATCO, Ovonics, the Defense Advanced Research Project Agency (DARPA), Sacramento Municipal Utility District, Southern California Edison, the United States Department of Energy, and others. The UC Davis PHEVs won several DOE/USCAR "Future Car" and "Future Truck" national competitions.

Inspired by his work as an EV1 propulsion system engineer, Jeff Ronning began developing concepts for plug-in hybrids in the mid-1990s at then Delco Remy, Division of GM. EV1 prototypes were sometimes attached with "range-extender" trailers, developed by Alan Cocconi of AC Propulsion. These trailers were simply rolling gen sets that could supply power for long trips. It was only natural to conceive of an EV1 with a small turbo-alternator on board (1995 internal publication). External publications (SAE 971629 and 1999-01-2946) followed expounding the merits of using electrical energy for most local travel and proving it with the data from the US DOT. "Unlimited EV" and "Battery Dominant Hybrid" as well as "Energy Hybrid" were the given names for the architecture because the term "plug-in" hybrid coined by Dr. Andy Frank was considered at odds with Toyota's position that Prius did not need to be "plugged in" and their opinion that plugging was inconvenient. In 1997 (ten years before Volt), an internal project at the new spin-off, Delphi Corporation, began to convert an EV1 to a PHEV. However, the project was canceled by the corporate directors of technology.

In 1994, the Esoro H301 two-door, four passenger plug-in hybrid sedan was built in Switzerland by the vehicle prototyping company Esoro AG. Four such prototypes are still on the road. The lightweight (710 kg/1565 lb) vehicle featured a 360 cc engine in parallel with a 34 kW air-cooled AC induction motor. The 9 kWh nickel-cadmium battery could be recharged in four hours from a 220 V electrical wall outlet, or from 30% to 80% state of charge in about two hours at a steady speed of 120 km/h.

In 1998, Audi premiered a second iteration of the Duo plug-in hybrid, based on the Audi A4, at the Frankfurt Motor Show. The 1998 Audi Duo featured a parallel configuration similar to its predecessor. At the time, hybrid propulsion was considered as a promising solution to Europe's inner city emissions problems. Audi AG leased ten Duo PHEVs to Solarmobilverein Erlangen in the city of Erlangen, Bavaria as part of ELCIDIS (Electric Vehicle City Distribution), an advanced mobility project funded by the European Commission. Solar recharging stations were envisioned, but were not built. The fleet trial ended in August 2001.

About sixty 1998–1999 Audi Duo PHEVs were built. However, few customers were prepared to pay twice the price as the base model A4 equipped with an identical diesel engine, and series production was stopped.

Sign in to keep reading

17 more chapters are free with a Lably account.

More in Environment