Types Of Gas An Audi A4 Takes (Explained)

In its 5th Generation, the Audi A4 has proven itself a worthy competitor to the likes of the BMW 3-Series and the Mercedes C-Class. It is hard to deny the executive stance and the luxury prowess of the A4 sedan. We are here to look at all the fuel-related topics for the Audi A4 so let’s dive right in.

All generations of Audi A4 manufactured from 2004 onwards take regular unleaded gasoline with a minimum octane rating of 87. However, Audi recommends using premium gasoline with an octane rating of 91 for optimum performance.

That’s the quick answer and we’ve seen similar recommendations across many Audi models from the Q3 to the Q8 premium fuel is standard.

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Does The Audi A4 Require Premium Gasoline?

2016 – Present

The Audi A4’s current generation is offered with two engines, both with 2.0-liter displacement. One of them is a higher output engine producing 261 horsepower than the 201 horsepower of the lower power variant. Both are gasoline engines, and as per the Audi A4’s user manual, a minimum of 87-grade octane fuel type is what Audi suggests; however, 91-octane is recommended for optimum performance.

That’s common across most Audi vehicles, whether you’re talking about the A4 or the A8, premium fuel is what Audi recommends.

Engine	Fuel Requirement
2.0-liter inline-four (201 HP)	87-octane minimum, 91 recommended
2.0-liter inline-four (261 HP)	87-octane minimum, 91 recommended

2008 – 2016

The Audi A4’s 4th generation, also known as B8, brought along a 2.0-liter inline-four — along with a 3.1-liter and a 3.2-liter six-cylinder engine. It was suggested by Audi to use a minimum octane rating of 87 for fuel to be used on both engines, however, 91-octane was recommended for best performance.

Engine	Fuel Requirement
3.2-liter Six-Cylinder Engine	87-octane minimum, 91 recommended
3.1-liter Six-Cylinder Engine	87-octane minimum, 91 recommended
2.0-liter Inline Four-Cylinder Engine	87-octane minimum, 91 recommended

2004 – 2008

The Audi A4’s 3rd generation was known as B7. The B7 Audi A4 was offered with two four-cylinder engines displacing 1.8 and 2.0 liters. The 6-cylinder engines were offered with 3.0 and 3.1-liter displacements. All these engines take a minimum of 91-octane gasoline.

Engine	Fuel Requirement
3.1-liter Six-Cylinder Engine	91-grade octane minimum
3.0-liter Six-Cylinder Engine	91-grade octane minimum
2.0-liter Inline Four-Cylinder Engine	91-grade octane minimum
1.8-liter Inline Four-Cylinder Engine	91-grade octane minimum

2000 – 2004

The B6 Audi A4 2nd generation comes with three engine displacements. A 1.8-liter Inline four-cylinder engine, a 2.8-liter six-cylinder, and a 3.0-liter six-cylinder engine. 87-octane was recommended at the minimum, but 91-octane is recommended for the best performance.

Engine	Fuel Requirement
3.0-liter Six-Cylinder Engine	87-octane minimum, 91 recommended
2.8-liter Six-Cylinder Engine	87-octane minimum, 91 recommended
1.8-liter Inline Four-Cylinder Engine	87-octane minimum, 91 recommended

1994 – 2000

The first generation of Audi A4 came with two engine displacements. There was a 1.8-liter inline four-cylinder engine and a 2.8-liter six-cylinder engine. Once again, 87-octane is the minimum octane level, whereas 91-octane is recommended.

Engine	Fuel Requirement
2.8-liter Six Cylinder Engine	87-octane minimum, 91 recommended
1.8-liter Inline Four-Cylinder Engine	87-octane minimum, 91 recommended

If you’re interested in the different gasoline requirements for all Audis, please read the article we just linked.

What Types Of Gasoline Can And Can’t Be Used?

In today’s world, many different types of gasoline are available to choose from. It means more profound knowledge of what to use and avoid is required. Let’s look at them one by one and educate ourselves more.

Reformulated Gasoline

Reformulated gasoline is a particular fuel type that is greener and cleaner in combustion. It is readily available at various gas stations, and many car owners use RFG. It is mainly a result of environmental focus, and engineers came up with RFG to protect the environment.

Given the environment-friendliness of RFG, one might expect some suggestions from Audi. But Audi remains neutral by neither suggesting for nor against using RFG. However, from experience, we know that carmakers recommend reformulated gasoline whenever possible.

Audi, as we’ve also mentioned in the Audi A3 fuel type or the Audi A5 fuel type, even the Audi Q3 fuel type, and other models, doesn’t explicitly recommend reformulated gasoline in the owner’s manuals because it’s a German brand, and RFG doesn’t exist in Europe.

Gasoline/Oxygenated Blends

Audi also takes the use of ethanol seriously for their cars. As per the owner’s manual of the Audi A4, ethanol-blended fuels may be used for the Audi A4, but to do so, one must ensure that the ethanol blend should not exceed 15% for model years made from 2015 onwards. A4 made before 2015 (up until 2014) take a maximum of 10% ethanol.

E-85

Many high-performance vehicles use ethanol-blended fuels for their cars. A very common type of ethanol-blended gasoline is E-85. The 85 in E-85 denotes 85% ethanol blended with 15% regular gasoline. It is a very high ethanol concentration blend, and a vehicle needs to be E-85 compatible to use it.

In the case of the Audi A4, only some engines are compatible with FlexFuel (E85).

Manufacturers leave different indications or markings of a vehicle’s E-85 compatibility. A common one of these indications is a Flex-Fuel badge found on your vehicle. The other indication is the E-85 marking on the vehicle’s fuel cap. If either of these is available, your vehicle is E-85 compatible.

While using ethanol-blended fuels, some symptoms and precautions become mandatory. The precautions one needs to ensure are:

• 11 liters minimum of fuel should be filled at the time of refueling
• After refueling, the vehicle should be kept running for at least 7 miles or more

The symptoms linked with the use of E-85 fuel are also attention-worthy. These are:

• Hard starting and unsmooth idling
• Residue build-up and possible corrosion due to deposit formation

Gasoline With Added Materials

Gasoline may be added with different materials for different purposes. Some additives are cleaning agents, and some are detergents available today at various gas stations.

However, it’s good to know that Audi strongly advises against using additives in your A4. This is because these additives can contain materials such as silicon or metallics that will seriously damage the engine and the fuel system.

Therefore, it’s recommended that you buy fuel that already has all the proper additives mixed into it. This kind of fuel can be purchased at certified TOP TIER gasoline retailers. These retailers sell gasoline that will provide the optimal performance for your engine and clean it as well as possible without damaging it. You can find a retailer at toptiergas.com.

Gasoline With MMT or MTBE

MMT is the abbreviation for Methylcyclopentadienyl Manganese Tricarbonyl. It was sold as a supplement when it was introduced. Later on, it was marketed and sold as an octane enhancer. Although Audi doesn’t suggest using MMT, or MTBE, also an octane enhancer, may be used.

MTBE or methyl tertiary butyl ether is also referred to as an oxygenate. It assists with emissions reduction and improving fuel economy. Audi suggests the below for using MTBE:

• The minimum octane rating must be 87 AKI or higher
• The blend must not exceed 15% MTBE

What If I Hear A Knocking Noise From The Engine After Refilling?

Engine knocking can be caused by using fuels with lower octane grades than recommended. In the case of the Audi A4, it is associated with fuels at an octane rating lower than 87. This knocking sound is also known as spark knock.

This can easily be fixed by using fuels with higher octane grades. As recommended by Audi in their owner manuals, premium gasoline is something every car owner is encouraged to use. Fuel with octane grades equal to or above 91 is a good fit to fix engine knocking.

However, if you hear loud engine knocking, it´s best to stop the car immediately and call your dealer. Most likely, your car needs to be drained of its fuel, and the fuel filter will need to be replaced.

Finally, it´s good to know that slight engine knocking is a normal occurrence, especially if you´re towing with the car or temporarily using gasoline with an octane rating between 87 – 91 (which is lower than recommended but still safe in most cases).

Does The Audi A4 Have Good Gas Mileage?

As can be expected, the fuel economy of the Audi A4 is reasonable, but it’s certainly not the most fuel-efficient sedan out there. Below, we’ve outlined the combined city and highway MPGs per generation.

2016 – Present

Engine	Combined MPG	City MPG	Highway MPG
2.0-liter Inline Four	27	24	34

2008 – 2016

Engine	Combined MPG	City MPG	Highway MPG
3.2-liter Six-Cylinder Engine	20	17	26
3.1-liter Six-Cylinder Engine	21	18	27
2.0-liter Inline Four	24	21	30
2.0-liter Inline Four (E85)	18	15	22

2004 – 2008

Engine	Combined MPG	City MPG	Highway MPG
3.1-liter Six-Cylinder Engine	19	15	25
3.0-liter Six-Cylinder Engine	21	18	26
2.0-liter Inline Four	22	19	27
1.8-liter Inline Four	23	20	27

2000 – 2004

Engine	Combined MPG	City MPG	Highway MPG
3.0-liter Six-Cylinder Engine	21	18	26
2.8-liter Six-Cylinder Engine	23	15	26
1.8-liter Inline Four-Cylinder	23	20	27

1994 – 2000

Engine	Combined MPG	City MPG	Highway MPG
2.8-liter Six-Cylinder Engine	21	18	26
1.8-liter Inline Four	24	21	29

What’s The Gas Tank Size Of An Audi A4?

The fuel tank capacity gives the car owner an idea of how far the vehicle can travel with a full tank. Let’s look at the fuel tank capacity for the Audi A4. The first-gen A4 had a 16.4 gallons tank, whereas this was increased to 18.5 gallons for the 2nd and 3rd generations. The 4th generation A4 had a 16.1 gallons fuel tank. Gen 5 of Audi A4’s AWD had 15.3 gallons, and FWD had 14.3 gallons of fuel tank capacity.

Generation	Gas Tank
5th Generation AWD	15.3 Gal
5th Generation FWD	14.3 Gal
4th Generation	16.1 Gal
3rd Generation	18.5 Gal
2nd Generation	18.5 Gal
1st Generation	16.4 Gal

Sources

• Audi A4 User Manual 2022
• Audi A4 User Manual 2019
• Audi A4 User Manual 2015
• Audi A4 User Manual 2012
• Audi A4 User Manual 2008
• Audi A4 User Manual 2005
• Fuel Economy of Audi A4
• Audi A4 Wikipedia