After years of low sales and tepid government support, U.K. plug-in electric car sales are taking off, five years after the first modern electric cars hit the road.

Sales steadily increased during 2015, but really took off in the first quarter of this year.

From January through March, a total of 10,496 electric cars and plug-in hybrids were sold in the U.K., 23 percent more than during the same period in 2015.

DON'T MISS: European electric and plug-in hybrid sales for January-February 2016

In March there were a record 7,144 electric-car sales, surpassing the previous record of 6,104 for March 2015, according to Wards Auto.

That's roughly two-thirds of the total number sold in the U.S., which has five times as many people.

U.K. sales are on track to exceed the total for last year, when more electric cars were registered than the previous five years combined, according to the Go Ultra Low auto-industry advocacy group.

Renault Zoe and Kangoo ZE electric cars on the Outer Hebrides

Renault Zoe and Kangoo ZE electric cars on the Outer Hebrides

Over the past 12 months, the U.K. reportedly ranked as the second-largest market for electric cars in Europe, behind The Netherlands.

The U.K. government has offered purchase incentives to buyers of new electric cars and plug-in hybrids since 2011, but that seems to have only recently had a significant impact.

First-quarter 2016 represents the best period of plug-in car sales since the program started, Go Ultra Low says.

ALSO SEE: U.K. Extends Green-Car Grants To Double Buyers By 2018 (Dec 2015)

The most recent figures show 58,000 vehicles registered with the program, which will now run through 2018.

It was originally set to expire this year, but the government decided to continue with £400 million ($595 million) funding, which it expects to cover up to 100,000 car buyers.

The new round of funding brings updated rules meant to emphasize battery-electric and hydrogen fuel-cell cars over plug-in hybrids.

2016 Nissan Leaf

2016 Nissan Leaf

Vehicles with a zero-emission range of more than 70 miles—with either battery or fuel-cell power—are eligible for the largest grant of £4,500 ($6,696).

Plug-in hybrids are eligible for a grant of £2,500 ($3,720), with a newly-added a £60,000 ($89,281) cap on purchase price.

Beginning last month, a £500 ($744) grant for home charging stations also became available.

MORE: Younger Car Buyers In U.K. Want Electric Cars Far More Than Older (Oct 2015)

The grant program has certainly helped, but the U.K. government has also been slow to adopt measures promoting the expansion of electric-car charging infrastructure.

It's also come under fire from environmental groups, who believe recent efforts to limit air pollution from vehicle exhaust in urban areas weren't aggressive enough.

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