Tuggeranong's Margaret and Michael Thompson never lie awake at night worrying about petrol prices.
Mrs Thompson's 18-month-old Holden Volt has used just 40.8 litres of petrol in the last 12,124 kilometres, an average of 0.3 litres per 100km, while Mr Thompson's new Tesla S consumes no fossil fuel at all.
The family owns two of the 167 electric vehicles now registered in the ACT, an increase of 40 per cent over the past 12 months.
Because the Thompsons are classic early adopters who made headlines when they built the equivalent of a six-star energy rated house, complete with geothermal heating and cooling, 20 years ago and have solar panels feeding electricity back into the grid they pay little or nothing to power the cars.
"We have switched to off-peak to recharge the cars which means each charge technically costs about one dollar a day," Mr Thompson said. "Because we are usually putting more power into the grid than we are taking out the real cost is zero."
While some of their neighbours pay up to $2000 to run gas heating over the winter quarter the Thompson's electricity bill is usually about $500 a quarter in credit.
"We were among the first people to take up the ACT Government's 50.5 cent a kilowatt hour feed-in tariff and have a four-kilowatt solar array on the roof," Mr Thompson, who is the secretary of the ACT Electric Vehicle Council, said. "Electric cars seemed the logical next step."
The ACT Government is preparing a low vehicle emission strategy and the council has lodged a submission proposing additional incentives for electric cars.
While the cars are expensive; the Tesla cost $187,000 and Volts retail around the $60,000 mark, Mr Thompson said like the family's earlier investments in energy efficiency, they make economic sense.
"These are 10-year cars; not three-year cars," he said. "If you keep them that long the figures do stack up. Service costs are much lower – almost non-existent in fact – and the batteries and drive train (on the Tesla) are warranted for eight years."
Mrs Thompson, who drove a Toyota Prius for eight years, said there was no comparison between the hybrid and the Volt.
"I had a Prado (four-wheel-drive wagon) before we bought the Prius and that change cut our fuel costs by two thirds (from 15l/100km to 5l/100km)," she said. The Volt only uses petrol if it runs out of charge and, on the rare occasions that has happened, it changes over seamlessly."
The Thompson's have no "range anxiety" concerns.
"The Volt travels 68km on a charge," Mrs Thompson said. "That is more than enough to get me to work or the gym. If I need to go further the petrol engine (which powers an electric generator that then drives the electric motor) cuts in."
The Tesla, which does not have petrol backup of any kind, has a much greater battery range.
"The company claims 500km under ideal conditions," Mr Thompson said. "We drove it back from Sydney last week, about 350km, and when we arrived we had 115km of range left."
Mr Thompson, a self-confessed "technology tragic", caught the bug when he started working with computers 30 years ago. "I started the Dell office in Canberra and worked there for 13 years," he said.
A former championship rally driver, who raced Subarus for two decades, he said when the Tesla was first announced he knew he had to buy one.
"It is me as a car," he said. "It is high performance (0-100km/h in 3.8 seconds according to the factory) and I love the IT and high technology elements."