A side effect of green advertising has emerged in the form of ‘greenwashing’, which designates “the act of misleading consumers regarding the environmental practices of a company or the environmental benefits of a product or service” (Terrachoice, 2010). Till now, research has focused on ‘claim greenwashing’, the use of textual arguments in the ad that create a misleading environmental claim and ignored the potential ‘executional greenwashing’ effect, whereby nature-evoking elements (e.g., pictures symbolizing endangered animals or renewable sources of energy, backgrounds representing natural landscapes) in the ad execution may induce false perceptions of a brand’s greenness, whether intentionally or not on the part of the advertiser. This research addresses this gap by documenting the ‘executional greenwashing’ effect and identifying moderating factors (i.e., consumers’ knowledge about environmental issues in the product category, the display of environmental performance information) that may reduce or even remove its impact on consumers. Research on green advertising has largely drawn from the ELM framework (Petty & Cacioppo, 1981) to assess the impact of green cues on consumers’ brand attitudes (Hartmann & Apaolaza-Ibáñez, 2009). However a sole focus on the content of the advertising message may not be sufficient to understand consumers’ responses to it. There may be important variables that moderate the effects on the brand’s ecological image. One important individual moderator, in the tradition of the ELM, is consumer topic knowledge, i.e. knowledge related to the topic of the message, which influences the ability to process the message and the outcome of persuasive attempts (e.g. Alba & Hutchinson, 1991). In the context of ‘executional greenwashing’, the persuasive power of advertising executional elements representing nature may therefore differ depending on consumers’ topic knowledge of environmental issues in the product category. Consumers with such topic knowledge, referred to as “expert” consumers, are less likely to rely on and be influenced by the use of advertising executional elements representing nature, whereas “non-expert” consumers may be influenced through the peripheral route to persuasion, resulting in greater perception of the brand’s ecological image. Stated formally: H1. Advertising executional elements evoking nature have a positive influence on the brand’s ecological image for non-expert consumers, but not for expert consumers. One important contextual moderator is the type of relevant information provided in the advertisement. In this paper, we examine whether the display of environmental performance information, which was in fact selected by the European Community, can correct a potential ‘executional greenwashing’ effect. The Directive 1999/94/EC requires that car manufacturers selling within European countries provide information regarding new cars’ carbon emission to direct consumers’ choices towards greener cars. A potential additional benefit of environmental performance information is that this kind of objective information may also prevent greenwashing by helping consumers form an accurate perception of a brand’s image, regardless of the executional advertising setting. A central premise of the ELM is that consumers’ response to information differs depending on their level of knowledge about the issue at hand. Expert consumers should be more able to treat the environmental information provided, therefore following a central route of persuasion (Alba & Hutchinson, 1991). Their brand evaluation should be formed based on the objective environmental performance provided, which are strong arguments, and not from the visual and sound executional elements manipulated in the ad (conversely for non-expert consumers). H2a. For non-expert consumers, advertising executional elements evoking nature enhance the brand’s ecological image, whereas the level of the environmental performance indicator (EPI) does not influence it. H2b. For expert consumers, the level of the EPI damages the brand’s ecological image, whereas advertising executional elements evoking nature do not influence it. Considering the relative efficiency of specific formats to display environmental performance information, we tested the traffic-light type of label, inspired by the energy appliance label program compulsory in Europe. The label format is crucial, especially if it can reduce the perceived costs of searching and processing this information and offer a comparison baseline. In the context of the EPI display, a traffic-light representation of the raw information about emission rates showing value ranges associated to color codes should may help expert and non-expert consumers calibrate environmental performance information, therefore counterbalancing the ‘executional greenwashing’ effect. H3. For experts and non-experts, the presence of a traffic-light label removes the effect of advertising executional elements evoking nature on the brand’s ecological image.