Almost half of Scotland's electric vehicle charging points could be lying unused, according to a study.
The RAC Foundation said it believes about 1,100 electric cars and vans are now on the road in Scotland.
But it said official data suggested the country's charging network was running below capacity.
The foundation analysed data - which relates to one month only - from Transport Scotland.
The statistics from last August, which were released under freedom of information rules, showed that 217 of the 482 units in the ChargePlace Scotland network were not plugged into at all during that month.
The remaining 265 (55%) were used at least once.
ChargePlace Scotland is the initiative behind Scotland's free charge point network.
There were some notable exceptions to the Scotland average, however, with all the charging units in Edinburgh, Falkirk and Stirling used at least once in August.
Overall that month, there was a total of 2,885 individual charging sessions in Scotland.
Of these sessions, 46% took place in three cities - Edinburgh, Dundee and Glasgow.
The most heavily-used charging unit was at Janet Brougham House, a care home in Dundee, which recorded 103 charging sessions during the month.
The next most heavily-used locations were Edinburgh's Victoria Quay (80 sessions) and Ingliston Park and Ride (61 sessions).
Prof Stephen Glaister, director of the RAC Foundation, said: "The encouraging news is that electric car sales in the UK are at last showing signs of improvement, but we still have a charging network in Scotland that is running below capacity.
"Part of the reason for installing public charge points is to help drivers overcome their fear of range anxiety, but this does not come cheap.
"This data also suggests a good proportion of charge points are located on private premises including council sites. This is encouraging as it was always envisaged that fleet operators would lead the way in the electric revolution."
He said he hoped the analysis would give an indication of where further money should be spent and where extra infrastructure might be needed.
'Distance to go'
WWF Scotland director Lang Banks said: "Alongside measures to reduce the total number of cars on our roads, a significant shift to electric vehicles will be needed to help Scotland reduce climate change emissions from the transport sector.
"These figures demonstrate that we've a distance to go before electric vehicles become a common sight on our roads.
"We'd therefore encourage the Scottish government to continue support efforts to speed up the roll-out of climate-friendly cars as well as to reduce the need for people to drive in the first place."
A Scottish government spokesman said: "We want to give drivers the confidence to make the same journeys they would in a petrol or diesel car, and with over 600 publicly available charge points now installed across Scotland we are building a network which can accommodate an ever-increasing demand.
"To help promote uptake, we have also supported local authorities and businesses to install charge points on their own premises and help them replace their fleets with cleaner, electric alternatives.
"We also pay for the installation of domestic charge points, providing EV drivers with the convenience of charging at home."