Ford has registered the "Mach 4" trademark, fueling rumors about a four-door Mustang. Is a new era for the iconic pony car on the horizon?

The company recently filed to trademark the ‘Mach 4’ name in the United States. Last year, Ford reportedly showed dealers a sketch of a possible four-door Mustang. The idea of an extended Mustang lineup isn’t exactly a groundbreaking concept.

Ford revived the Boss 302 with the fifth-generation Mustang, for the 2012 and 2013 model years, equipping it with a 444-hp 5.0-liter V-8, an upgraded suspension, a sports exhaust, and unique styling touches. There was also a Laguna Seca package that added extra goodies.

A new trademark filing from Ford suggests the much-rumored four-door Mustang may indeed be in the works. Uncovered by Ford Authority, the Blue Oval recently submitted paperwork to trademark “Mach 4.” The February 25 application with the United States Patent and Trademark Office (USPTO) states that its usage is for “motor vehicles,