The 2004 Audi A6 has a fuel tank capacity of 18.5 to 21.7 gallons (70–82 liters), depending on the trim. The most common size is 18.5 gallons, used on 6 trims.
A full tank is good for roughly 426–477 highway miles or 296–333 miles around town, going by the EPA ratings.
020 gal40 gal
21.7 gal · Bigger than 65% of 2004 models we list.
3.0 quattro AWD 4dr Sedan3.0L 6cyl 5A · AWDMPG 16 / 23Range 296 / 426 mi
3.0L 6cyl 5A
AWD
18.5 gal70 L
16 / 23
296 / 426 mi
4.2 quattro AWD 4dr Sedan4.2L 8cyl 5A · AWDMPG 15 / 22Range 326 / 477 mi
4.2L 8cyl 5A
AWD
21.7 gal82 L
15 / 22
326 / 477 mi
No trim matches all of these filters.
Tank figures are the manufacturer's rated capacity, sorted smallest tank first. Range is tank size times EPA city or highway MPG.
How far a 2004 Audi A6 goes on a tank
Gallons left and the distance they cover at each mark on the fuel gauge, at EPA city and highway mileage. At the combined rating of 19 MPG, a full 18.5-gallon tank covers about 352 miles.
Gauge
Gallons
Highway miles
City miles
Full
18.5
426
296
3/4
13.9
319
222
1/2
9.3
213
148
1/4
4.6
106
74
1/8
2.3
53
37
Over 15,000 miles a year (the EPA's yearly estimate) this configuration uses about 789 gallons, roughly 43 full tanks.
Fuel gauges aren't perfectly linear and the low-fuel light comes on with a few gallons still in the tank, so plan your stop before the last eighth.
Other 2004 sedans of a similar size, one model per brand.
2004 Audi A6 fuel system recalls
NHTSA lists 2 fuel-system recalls for the 2004 Audi A6, out of 4 recalls in total. A recall applies only to the vehicles named in it, so check your VIN.
Storage · Tank assemblyMay 3, 2011 · NHTSA 11V267000 · Volkswagen Of America, Inc · 5,992 vehicles
Volkswagen is recalling certain model year 2001-2004 audi a6, model year 2002-2003 s6 and model year 2003 rs6 vehicles equipped with 4.2l engines and manufactured from june 19, 2001, through june 8, 2004. The aging of the plastic material in the fuel tank rollover valve combined with bending stress from the aluminum ventilation line to the rollover valve nipple may lead to cracking of the nipple. If this happens, a fuel leak may result.
Risk and remedy
Risk: A fuel leak in the presence of an ignition source could lead to a vehicle fire.
Remedy: Dealers will reinforce the nipple on the rollover valve to prevent leakage or repair the cracking at the nipple. The recall is expected to begin during june 2011. Owners may contact audi at 1-800-822-2834.
Storage · Tank assemblyApr 8, 2008 · NHTSA 08V157000 · Volkswagen Of America, Inc · 68,240 vehicles
Volkswagen is recalling 68,240 my 2001-2004 audi a6 quattro vehicles equipped with 2.7l, 2.8l, or 3.0l engines and my 2001-2005 allroad quattro vehicles equipped with 2.7l or 4.2l engines. The aging of the plastic material in the fuel tank rollover valve combined with bending stress from the aluminum ventilation line to the rollover valve nipple may lead to cracking of the nipple. If this happens, a fuel leak may result.
Risk and remedy
Risk: A fuel leak in the presence of an ignition source could lead to a vehicle fire.
Remedy: Dealers will reinforce the nipple on the rollover valve to prevent leakage or repair the cracking at the nipple. The recall began on june 27, 2008. Owners may contact audi at 1-800-822-2834.
What is the fuel tank capacity of the 2004 Audi A6?
The 2004 Audi A6 holds between 18.5 and 21.7 gallons, depending on the trim. 18.5 gallons is the usual size; the 21.7-gallon tank comes on the 4.2 quattro AWD 4dr Sedan (4.2L 8cyl 5A).
How many gallons and liters does the 2004 Audi A6 gas tank hold?
The 2004 Audi A6 tank holds 70–82 liters, or 18.5–21.7 gallons in US gallons.
Which 2004 Audi A6 has the biggest gas tank?
The 21.7-gallon tank is on the 4.2 quattro AWD 4dr Sedan. The smallest tank, 18.5 gallons, is on the 2.7T S-Line quattro AWD 4dr Sedan.
Does AWD change the 2004 Audi A6 gas tank?
Yes. AWD: 18.5–21.7 gal; FWD: 18.5 gal.
How far can a 2004 Audi A6 go on a full tank?
About 426–477 miles on the highway and 296–333 miles in town, going from full to empty at its EPA ratings. Expect less in practice, since nobody runs the tank dry.
How many miles can a 2004 Audi A6 go on a quarter tank?
About 106 highway miles or 74 in town from the 18.5-gallon tank, which has roughly 4.6 gallons left at the quarter mark. Gauges aren't exact, so treat that as a guide.
What gas does the 2004 Audi A6 take?
Premium unleaded (required). The label inside the fuel door confirms it for your car.
How much does it cost to fill up a 2004 Audi A6?
At the US average of $5.28 a gallon for premium (EIA, week of October 26, 2026), filling the 18.5-gallon tank from empty costs $97.68. It ranges from $84.55 in the Gulf Coast to $117.66 in California.
How much does a full tank of gas weigh in a 2004 Audi A6?
About 135 pounds for the 21.7-gallon tank. Gasoline weighs roughly 6.2 pounds a gallon.
Does the 2004 Audi A6 have a bigger gas tank than the Mercedes-Benz E-Class?
Yes. The 2004 Audi A6 holds up to 21.7 gallons; the 2004 Mercedes-Benz E-Class holds up to 20.6.
Has the 2004 Audi A6 had a fuel pump or fuel system recall?
Yes. NHTSA lists 2 fuel-system recalls for the 2004 Audi A6: 11V267000 (storage · tank assembly); 08V157000 (storage · tank assembly). Check your VIN at nhtsa.gov/recalls to see if your car is affected.
Sources
Tank sizes: manufacturer-rated capacities from US-market specifications, checked against independent references. Updated October 2026.
MPG and range: EPA ratings (fueleconomy.gov). Range is tank size times EPA MPG.
Fuel prices: U.S. Energy Information Administration, week of October 26, 2026 (this week's prices).