The phrase, "the most powerful in its class", may be true as "class" is not defined. According to the case, trucks similar to the Mammoth are used for hauling heavy equipment but the Mammoth is not suited for hauling. This would mean that the Mammoth would be in a different class from the hauling trucks, or in a class of its own. However, it does have a powerful engine which supports the claim that it is the most powerful in its class. All the above support the tagline "The Mammoth. Power, Beauty, Style."
The advertisement focuses on qualities not necessarily connected with the product but I don't think this has been done unduly. The company used its good reputation for luxury sedans and sports cars, products which evoke power, beauty and style. The Mammoth advertisement may be targeting the same market as those for its traditional products, considering that the truck was not really built for hauling heavy equipment. The Mammoth can be viewed as simply another vehicle sporting a different design, a hauling truck design. But in the same way that luxury sedans and sports cars serve their intended customers for power, beauty and style, the Mammoth is also being sold to do this, especially since the advertisement depicted the owner getting into the truck in a tuxedo and driving to the opera.
It is permissible fo