According to QSRmagazine.com, Dunkin' had the fastest drive through time of several fast food restaurants.  The article made me do math, which I wasn't thrilled about, but the average wait time from speaker to order was 4.25 minutes.  Dunkin' wait time was 3.61 minutes.  Not bad for a little coffee place that started in New England, in Quincy, Mass.  

Fun fact from Wiki, Dunkin' Donuts was originally called Open Kettle, but then the owners changed the name after talking with company executives.

While I'm on the topic of the drive thru, may I please ask if you have a complex order like, 3 sandwiches, all special with additions and/or subtractions, 7 coffees and a few muffins, don't go through the drive thru.  Get out of your cah and head in to Dunks.  Wait in the inside line.  'Cuz if I'm behind you and you order all that stuff when all I want is a black coffee?  There's gonna be some horn honkin.  (not really, I'll just sit there and judge you silently.)