Restaurant chains have a formula, but the fact is, the are efficient. A bigmac you get in NJ will taste very different than the very same bigmac you get in the midwest. They use suppliers closest to them, farms for the tomatoes and beef closest to them, sure the special sauce remains the same, as do the ingredients, but the flavors can easily change from one region to another since their staple products come from different distributors... Never had a fatburger, but have had sonic and wunderburger in TX... not a big fan of fastfood, especially since its hardly consistent as it once was...