Magazine adverts by car manufacturer Lexus misled consumers over carbon emissions, the Advertising Standards Authority (ASA) has ruled.
The Lexus RX400h is a hybrid sports utility vehicle
The company's promotion for its RX400h hybrid sports utility vehicle (SUV) had the headline "high performance, low emissions, zero guilt".
The ASA said this implied the car's emission rate was low compared with all other cars, not just other SUVs.
Lexus said it thought consumers would fully understand the advert's claims.
The ASA upheld 10 complaints about the advert, which also stated the 4x4 car had "category-leading low CO2 emissions" at 192g/km.
The ASA said Lexus had breached rules relating to truthfulness, comparisons and environmental claims.
The watchdog also said readers would infer from the headline that: "the car caused little or no harm to the environment, which was not the case, and had low emissions in comparison with all cars, which was also not the case."
Lexus company spokesman Scott Brownlee said: "We weren't trying to be misleading and any changes that are needed, we will certainly make.
"It wasn't that we were trying to make a claim that was unsustainable.
The car has low emissions compared to, say, a Land Rover or another 4x4. That is the message we were trying to communicate."
Friends of the Earth's senior transport campaigner Tony Bosworth said: "Hybrid engines are part of the answer to cutting carbon emissions from cars, but just because a car has a hybrid engine doesn't make it pollution-free.
"Car manufacturers must put more effort into building more fuel-efficient vehicles, and advertise them accurately and responsibly."