Only NFL team to go undefeated?

Answer 1

Since the National Football League created a playoff structure in 1932, the only team to go undefeated through a full season is - as is well known, the 1972 Miami Dolphins. The 1972 Dolphins went 14 and 0 in the regular season and won their three post-season games to finish 17 and 0.

Three other teams have had undefeated regular seasons since 1932: the 1934 and 1942 Chicago Bears and 2007 New England Patriots (whose deriders called the "Cheatriots" because of the "Spygate" controversy). The 1934 and 1942 Bears were both beaten in the NFL Championship Game, finishing 13-1 and 11-1 respectively; whilst the 2007 Patriots won two games to be 18-0 before being upset in Super Bowl XLII by the New York Giants. In the process the 2007 Patriots achieved a start that has never been managed even in the long-season sports of baseball, ice hockey or basketball.

Answer 2

The Miami Dolphins went undefeated in 1972 during the 3rd year of being coached by Don Shula.

Answer 3

Soon to be Green Bay Packers!