Car Talk is structured as a call-in radio show: listeners call with questions related to motor vehicle maintenance and repair. Most of the advice sought is diagnostic, with callers describing symptoms and demonstrating sounds of an ailing vehicle while the Magliozzis make an attempt at identifying the malfunction.
While the hosts pepper their call-in sessions with jokes directed at both the caller and at themselves, the depth and breadth of their knowledge of automobiles is extensive, and they are usually able to arrive at a diagnosis and give helpful advice. Also, if a caller has an unusual name, they will inquire about the spelling, pronunciation, and/or origin of their name. They may also comment about the caller’s hometown.
The Magliozzis previously took a break at approximately the half-hour mark of the show. More recently, two breaks divide the show into approximately 20-minute segments referred to as the “three halves” of the show. Between segments a piece of music related to cars will play.
The show opens with a short comedy segment, typically jokes sent in by listeners, followed by eight call-in sessions. The hosts run a contest called the “Puzzler,” in which a riddle, sometimes car related, is presented. The answer to the previous week’s “Puzzler” is given at the beginning of the “second half” of the show, and a new puzzler is given at the start of the “third half.”
The hosts give instructions to listeners to write answers addressed to “Puzzler Tower” on some non-existent or expensive object, such as a 26-dollar bill or an advanced digital SLR camera. This gag initially started as suggesting that the answers be written “on the back of a twenty dollar bill.” A running gag concerns Tom’s inability to remember the previous week’s Puzzler without heavy prompting from Ray. For each puzzler, one correct answer is chosen at random, with the winner receiving a $26 gift certificate to the Car Talk store, referred to as the “Shameless Commerce Division.” It was originally $25, but was increased for inflation after a few years. A recurring feature is “Stump the Chumps”, in which they revisit a caller from a previous show to determine the effect, if any, of their advice. A similar feature began in May 2001, “Where Are They Now, Tommy?”
Celebrities have been callers as well. Examples include Geena Davis, Morley Safer, Ashley Judd, Gordon Elliott, former Major League pitcher Bill Lee and astronaut John Grunsfeld calling from the Space Shuttle. There have been numerous appearances from NPR personalities, including Bob Edwards, Susan Stamberg, Scott Simon,Ray Suarez, Will Shortz, Sylvia Poggioli, and commentator and author Daniel Pinkwater. On one occasion, the show featured Martha Stewart as an in-studio guest, whom the Magliozzis twice during the segment referred to as “Margaret”.