Apparently Hyundai is trying to appropriate the same type of adverb-without-an-"ly" thing that Apple used so successfully with their "Think Different" campaign, only Hyundai is saying: "Live Brilliant". The thing is, when Apple used it, it worked, because it made sense, because it wasn't being grammatically incorrect; it was instead saying to think of something different, or think in a different way, in the same manner as one might use the colloquialism: "Think big". (In fact, I think it was a new twist on the old expression "Think big" in the same sort of way that Doyle Dane Bernbach did with their famous "Think small" campaign for Volkswagen in the 1960s. And it worked equally well for Apple, I'd say.) But I'm not sure this Hyundai tagline works in the same way; I think, rather, that it's trying to capture lightning in a bottle using a mimicking technique by simply dropping the "ly" off of their adverb and using a two-word sentence like Apple's famous campaign did. And while it is said that imitation is the sincerest form of flattery, and it tries to achieve the same result as its model, it's generally not nearly as good the second time around (although there are occasionally some standout exceptions where it improves upon the original. But such is not the case here.).
Here's an example of a Hyundai ad using this tagline:
http://www.youtube.com/watch?v=T3gqHWA3epU
