Since its launch in December 2010, owners of the Chevrolet Volt extended-range electric car have steadily racked up miles driven solely on electricity from the grid.
They recently reached a significant collective milestone: more than half a billion electric miles.
2013 Chevrolet Volt, Catskill Mountains, Oct 2012
The total is based on data from owners who let Chevy track their mileage via the Onstar telematics system, meaning that the actual total electric miles are likely up to 20 percent higher.
The total reflects the fact that most Volts operate on electric power from the grid, stored in their lithium-ion battery packs, the majority of the time.
According to General Motors, Volt owners do more than 63 percent of their driving on electricity, and travel an average distance of 970 miles between fill-ups.
And Volt owners showed their enthusiasm for zero-emission motoring right out of the gate.
In October 2011--just 10 months after the first Volt was delivered to a retail buyer--the Volt and the other two top-selling electric cars at the time (the Nissan Leaf and Tesla Roadster) had driven a combined 35 million miles on electricity.
2013 Chevrolet Volt - Driven, December 2012
Two years after it went on sale, Volts had racked up 100 million electric miles in the hands of owners. They achieved 200 million miles in June 2013, 300 million last October, and 400 million in February of this year.
The steeper curve reflects more Volts on the roads--more than 61,000 as of the end of May--so the next milestone should arrive commensurately quickly.
The number of electric miles driven per day rose from 537,634 in June 2013 to 923,077 in May 2014. If that figure rises slightly, to just 1 million miles per day, Volt owners could pass the 600 million-mile mark only three months from now.
At that rate of progress, it's only a matter of time before the Volt fleet will have racked up more than 1 billion miles of silent, emission-free driving.
[Our thanks to Matthew Klippenstein for collating Volt mileage data.]