On the subject of the Gas Guzzler tax...

Why is it that when I go to Dodge.com's "Build a Charger" site and price an SRT8 it adds the $2100 charge, but when I build a Daytona 5.7 it doesn't add anything? According to the formula mentioned by Paladin earlier and confirmed here there should be a $1300 charge for the 5.7. I guess we all assume the Tax to be the same for the Challenger with the corresponding engine. I'm just wondering if Dodge "forgot" to mention the GGT on the Charger 5.7.