The 2013 Audi A6, like its BMW 5-Series, Jaguar XF, and Mercedes-Benz E Class luxury rivals, has less interior space than you might think from the outside. Technically it's a five-passenger sedan, but with a smallish trunk and a a relatively skimpy middle (fifth) seat space in back, you'd likely be happier with the (arguably more stylish) four-passenger A7 hatchback if practicality is a top concern.
With an overall length of about 193.9 inches, the A6 is about the exterior size of many mid-size sedans, although Audi has tried to give this sedan the swept-back proportions of a rear-wheel-drive sport sedan, and that's cost some space. With about two more inches of height versus the A7 hatchback, there's a touch more headroom in the A6, though.
Front-seat accommodations in the A6 are superb, with lots of head, leg and knee room, though the A6's center console widens a bit and nibbles out a bit of the available space. We've found the power front seats to be supportive and exceptionally comfortable on long trips, and Audi recesses its headrests for far better comfort than the protruding active headrests on some other luxury cars. The front seats can be fitted with heating and ventilation controls.
The A7 and A6 have different rear-seat arrangements, and we're not convinced the extra seat in the A6 is worth it. The A6 has a slightly higher roofline and three seatbelts. It's true that two 6-foot passengers can fit back there, but knee room isn't exactly plentiful. The A7 doesn't offer the middle seat position, but its snug accommodations are tougher to get in and out of.
The A6's trunk isn't as large as the cargo space under the A7's hatchback. At 14.1 cubic feet, the A6 trunk is small even by luxury standards, and the cargo floor is somewhat high. A6 cars have fold-down rear seatbacks, but they don't fold flat.
And seemingly in following the tradition of German luxury sedans, there isn't all that much storage space for small items. The A6's cupholders are a tight fit for most drinks, unless you're pounding Red Bull. The console is shallow, and the glovebox is slim.
Fit and finish is a strength, as it usually is in Audis. The cabin filters out a lot of road noise and powertrain noise.