I don't think anyone can, but what if it was 300hp and then later released it was 296hp. 300hp sure looks a lot better than 296hp, and I bet a lot of people would buy a car/truck based on the fact they saw 300hp.
4hp won't make a big difference in performance, but in the advertising game it sure can. The first thing in the Titan commercials is "Most standard power in it's class." You think they care if the Titan beats another truck by 1hp, nope, they will still advertise it that it has the most power. It's like saying buy this product for under $400!!!!!!! And the cost is $399.99,,,doesn't really make a difference, but sure sounds better.
