Hyundai has released a version of its Sonata hybrid that has solar panels to help charge its battery.
The Korean car maker said up to 60% of the power for the car's battery could be supplied if the solar roof was used for six hours a day.
The panels would provide enough power to propel the Sonata for 1,300km (800miles) a year, it added.
Hyundai said it planned to offer the roof as an optional extra on other models in its range.
Fitting hybrids with panels that can harvest solar energy would boost fuel efficiency and lower carbon dioxide emissions said Hyundai.
It added that the mid-sized passenger car had an improved engine control system to ensure energy use was as efficient as possible.
Writing on the Digital Trends news site Stephen Edelstein said: "Hybrids like the Sonata have smaller battery packs than all-electric cars, so a solar roof can make a bigger difference in charging.
"Solar cells add cost and weight to cars, and it's unclear how effective they can be in the real world."
Hyundai is working on a second-generation solar roof that would be semi-transparent to help light the car's cabin.
The solar-roof equipped Sonata will be on sale in North America and Korea. Hyundai said it had no plans to sell it in other regions.
No price for the hybrid passenger car equipped with a solar roof has been given by Hyundai.
Reposted from BBC