The Advertising Standards Authority in England is an ad industry run group that regulates and monitors advertising and marketing and addresses consumer complaints about ads. When a company runs false or misleading ads and they don't respond to ASA direction to change the ads, ASA can refer the problem to the Office of Fair Trading and Ofcom, which are government agencies.
Recently the ASA looked into consumer complaints about an ad that Lexus was running for the RX400h that was misleading with the tagline "HIGH PERFORMANCE. LOW EMISSIONS. ZERO GUILT". Since the hybrid CUV has CO2 emissions of 192g/km compared to a European average of less than 160g/km the ASA didn't like the ad. Lexus responded that RX400h emissions were lower than any other vehicle in it's class but the ASA didn't think this was good enough and the ad implied that the emissions were low compared to all vehicles, which they aren't.
The ASA ordered Lexus not to imply that the RX caused little or no environmental harm relative to all cars if it wasn't true. Clearly this is a case of Toyota trading on a carefully cultivated green reputation that isn't always deserved. They certainly deserve credit for cars like the Prius, but many of the Lexus hybrids are not that impressive compared to many of the highest volume cars in Europe.
[Source: Advertising Standards Authority]