The C6 Audi A6 was built on the Volkswagen Group's D3 platform.
It had a transverse-mounted front engine and a longitudinal-mounted rear engine.
Available engines included a 2.0T inline-4 turbocharged petrol, a 2.7 V6 petrol, and a 3.2 V6 petrol.
Diesel options were a 2.5 V6 and a 3.0 V6.
The vehicle's suspension was composed of double wishbone front and rear multi-link systems.
Brakes were made up of ventilated discs at the front and solid discs at the rear, with optional ceramic disc brakes on certain trim levels.
The C6 Audi A6 was available in various body styles, including a four-door sedan and an Avant wagon variant.
The vehicle's interior included features like dual-zone climate control and a 10-speaker audio system on higher trims.
Optional safety features included adaptive cruise control with automatic emergency braking and lane departure warning systems.
Some markets offered an optional 'bi-xenon' headlight setup featuring LED daytime running lights.
The C6 Audi A6 had a claimed fuel economy of up to 8.4L/100km (29.1mpg) for the most efficient petrol engine variant, and around 5.9L/100km (47.7mpg) for the best diesel option.
In some regions, the vehicle came equipped with a standard panoramic moonroof on higher trim levels.
The Audi A6 C6 had a payload capacity of up to 570 kilograms (1,254 pounds).
It measured 4,846 millimeters (190.8 inches) in length and 1,832 millimeters (72.2 inches) in width.
Ground clearance was at a maximum of 140 millimeters (5.6 inches) with the standard suspension setup.
The curb weight ranged from around 1,660 to 1,830 kilograms (3,647-4,024 pounds), depending on engine choice and trim level.
Some countries made an optional adaptive air suspension system available for certain trims.
The C6 Audi A6 had a reported top speed of over 240km/h (149mph) with the most powerful petrol option.
It featured an all-wheel-drive Quattro system as standard on many trim levels, and some models had an electronic rear axle locking differential to enhance stability.
Certain markets offered a sport-tuned suspension package with firmer spring rates and different dampers for improved handling.
This generation of Audi A6 saw the introduction of Audi's MMI infotainment system, which featured an optional hard-drive navigation unit.
The vehicle had a trunk capacity of around 480 liters (17 cubic feet), expanding to about 1,200 liters (42.4 cubic feet) with the rear seats folded.
In some regions, buyers could opt for a three-spoke flat-bottomed steering wheel with shift paddles and a more aggressive design aesthetic on high-performance trims.
The Audi A6 C6's interior boasted features like optional leather upholstery, a 'black piano' trim option, and available power-adjustable front seats with lumbar support.
In the UK, the 2004 Audi A6 C6 was priced starting at around £23,500 (approximately $30,400 USD), for the base model with a 2.0T engine.
The vehicle featured an optional 'comfort' mode on its driver-selectable Dynamic Chassis Control system, which altered suspension stiffness and steering effort to prioritize ride comfort.
The C6 Audi A6 came equipped with features like heated mirrors, automatic headlight leveling, and rain-sensing windshield wipers as standard or optional features.
In certain markets, buyers could upgrade to an available navigation unit with a built-in rearview camera.
This generation of Audi A6 was produced from 2004 to 2008 in Europe, with some later models being available for purchase until 2010 in various countries.
The C6 Audi A6 had a claimed cargo capacity of up to 1,520 liters (53.7 cubic feet) behind the front seats when combined with its Avant wagon body style and an optional 'through-loading' floor panel that enabled better access to deeper areas of the cargo space.
It was offered with a wide range of trim levels across different countries and had varying specifications and features depending on market requirements.
The Audi A6 C6 featured advanced safety systems such as adaptive cruise control, which employed radar sensors to monitor traffic and adjust vehicle speed accordingly.
In some markets, the 2004 Audi A6 offered a remote parking feature, enabling drivers to park the car remotely using an external remote control unit.
This generation of the vehicle saw improvements in fuel efficiency, with some variants boasting up to 12% better economy than their predecessors.
The C6 Audi A6 had its interior trim upgraded to aluminum or wood on certain trims and models.
Some markets made available an adaptive cruise control system that could automatically apply the brakes when traffic stopped, even in the absence of a lead vehicle.
In various regions, buyers were given the option for an MMI infotainment system with voice commands and Bluetooth connectivity.
The Audi A6 C6 had its boot capacity expand to up to 1,700 liters (60 cubic feet) behind the front seats when combined with the optional 'comfort rear seats' package that included through-loading floor panels and a raised boot lip.
Certain models allowed for an electric tailgate operation on higher trim levels.
Some markets made available an 'Audi parking system plus', which employed sensors to provide visual warnings of obstacles in close proximity during reversing maneuvers.
The C6 Audi A6 featured LED fog lights as standard or optional equipment depending on model and market requirements.
It had its interior upgraded with features such as a driver information display showing vehicle speed, gear position, and outside temperature readings.
In the UK, the 2004 Audi A6 was also offered in higher trims featuring 19-inch aluminum wheels as standard or optional equipment depending on trim level.
The vehicle's engine management system was programmed to limit torque when shifting from a standing start to prevent wheel spin on slippery surfaces.
This generation of Audi A6 saw the introduction of their 'MMI with navigation' infotainment system featuring voice commands, Bluetooth connectivity, and an available 40-GB hard drive for storing music files.
The C6 Audi A6 came equipped with advanced driver assistance systems such as adaptive cruise control, lane departure warning systems, and automatic emergency braking capabilities on higher trims.
Some countries made available a range of interior trim upgrades including aluminum or wood options across various model lines.
Certain markets offered an optional 'black piano' trim upgrade featuring a premium black finish for the dashboard, door panels, and center console.
The vehicle's exterior design featured subtle updates compared to its predecessor with cleaner lines, improved aerodynamics, and an updated front bumper on some trims.
In Europe, buyers could opt for an available 'S line' sport package featuring a range of styling upgrades including more aggressive bumpers, side skirts, and a rear spoiler on select models.
The Audi A6 C6's interior featured ambient lighting as standard or optional equipment depending on model and market requirements.
Some trims were upgraded with power-adjustable front seats that could be heated, cooled, or ventilated depending on regional offerings.
This generation of the vehicle saw improvements in infotainment systems, allowing buyers to store a significant amount of digital content directly within their system's hard drive storage.
The C6 Audi A6 had its boot capacity upgraded to accommodate up to 1,750 liters (62 cubic feet) when combined with optional features such as through-loading floor panels and an electric tailgate operation on higher trim levels.
Some markets made available a special 'winter package' featuring additional features such as heated steering wheel, snow socks, and other regional upgrades for improved winter driving conditions.
This generation of Audi A6 featured upgraded front brake discs with ventilated design for enhanced stopping performance.
The vehicle's suspension was comprised of double wishbone front and rear multi-link systems designed to provide a comfortable ride while maintaining handling stability.
Some trims offered an optional 'comfort' mode on their Dynamic Chassis Control system that prioritized ride comfort over dynamic handling.
In various regions, buyers could opt for leather upholstery featuring contrasting stitching or piping depending on trim level and model line.
The Audi A6 C6 had a claimed top speed of 155mph (250km/h) for the most powerful petrol engine variant available in certain markets.