The car was revealed to the world via a live broadcast on the squad's YouTube channel.
The unveiling was moved inside the Lotus factory after the team's outdoor marquee was disrupted by strong winds.
Technical director James Allison said that while the E21 looked outwardly similar to its predecessor, it had undergone plenty of changes.
"There is a lot gone into it and it is going to be an exciting car," he said.
"The rules for 2013 are very, very similar to 2012 so you can expect a lot of family resemblance from the 2012 car, but the devil is in the detail and it adds up to a significant amount of performance.
"There are lots of new ideas and same concepts we have been pushing on with for a few years."
The Enstone team returned to the top step of the podium for the first time since its Renault era when Kimi Raikkonen won last year's Abu Dhabi Grand Prix, ending a victory drought dating back to Fernando Alonso's Japan 2008 triumph.
In a season of resurgence for Lotus, Raikkonen was a title contender for much of the year and finished third in the world championship in his first F1 campaign since 2009.
Raikkonen stays on for 2013, with team-mate Romain Grosjean retained despite an often erratic campaign in which impressive performances were punctuated by collisions, including a Belgian GP startline pile-up that earned him a race ban for the following event in Italy.