Actually, we're just being mean, it was apparently just a mistake that had a rather snowballing effect according to a Toyota spokesman, quoted by Automotive News: “A supplier developing site content used the image of the Benz V-6 engine as a placeholder during the production process. The image made it through the revision process without being replaced. The image has been removed.”
The image above represents a screenshot made by Jalopnik back when the glitch was still viewable on the Toyota website. The engine circled in yellow is a Mercedes-Benz three-liter V6, turbocharged diesel engine, internally-codenamed OM642 and found in different versions on a number of current three-pointed star models.
Story via Automotive News/Jalopnik