John Bowker develops electric dual-power car in early 1940s Adelaide, with 151km range and top speed of 38km/h

John Bowker's J.B. Electric Dual-Power Car at Montefiore Hill, Adelaide, after making a run around city streets in the early 1940s. The image is taken from films made by Laurence S. Casson 1934-1976 of South Australian events, now held by the State Library of South Australia and available on YouTube.
Adelaide engineer John Bowker, with financial backing from businessman W.J. Cowell, developed an electric dual-power car in the early 1940s that could travel for 94 miles (151 kilometres) before needing to be recharged and had a top speed of 24mph (38km/h).
At that time, it could be charged cheaply in AC or DC currents for a shilling a day. The electric dual-power motor car, designed to run on its own generated power, was developed at the Linden Park works of Bowker’s entrepreneurial J. B. Inventions Syndicate.
The government took Bowker’s invention seriously enough for the chairman of the substitute fuels committee (and former South Australian premier) Richard Butler to send Adelaide University’s professor H. W. Gartrell and professor W. H. Schneider, to inspect the J.B. Electric Dual-Power Car.
Adelaide University physics professor Kerr Grant and the Adelaide Electric Supply Company were sceptical about the project but, as the Electrical and Engineering Review (1942) pointed out, Bowker had achieved where a large American motor car company had failed after spending more than £20,000.
Bowker said months of hard work and road tests had investigated more than 150 ideas to find how to conserve or convert electrical energy. These idea were trimmed to 32 that were used, including: regenerating power driving downhill and also automatically when slowing the car; eliminating energy dissipating resistance control by an ingenious electrical remote control switching; supporting batteries in a cradle, maintaining road balance; an aircraft principle of body construction, giving strength with lightness; a novel shock absorber system; an auxiliary power unit for unlimited range and higher speed.
J. B. Inventions also promoted the car's advantages a low cost of manufacture, with simple components, all available locally; a long life, due a minimum moving parts; better manoeuvrability and acceleration in traffic; and “fire risk largely eliminated”.
The downsides of the car at that stage included rapid loss of charge in long journeys, reduced battery performance over time and the need to inspect and top up all the battery cells every few days. And, even in 1942, Bowker could see that the “the world is petrol minded and, secondly, the world demands speed and flexibility, even at the expense of economy”.