What Type Of Gas Does Audi A8 Take?

Premium vehicles like the Audi A8 always require premium fuel, right? While that’s mostly true, there’s some confusing nuance to it. 

But here’s the quick answer to get you fueled up and back on the road: 

Audi’s A8 owner’s manual recommends premium fuel with a minimum octane rating of 91. That’s true across all generations of the A8 except for the TDI diesel engines which require ultra-low sulfur diesel. While the A8 can be operated using regular unleaded 87 octane, per the owner’s manual, engine performance will be reduced. 

That shouldn’t be news to anyone who’s been around the Audi line and these are the same recommendations we see in similar models like the A7 or A5. Still, there’s more to dive into here so we’ll take a closer look at everything you need to know about fueling up your Audi A8. 

Let’s get into it! 

Fuel Requirements Based On Engine Type For All Generations Of Audi A8

Much like other members of Audi’s esteemed lineup, including models such as the A6 and A4, the A8 is designed with a penchant for premium fuel.

We’ll break it down by engine type and generation to get a clearer picture of the A8’s specs and why premium fuel just makes sense. But if you just want a snapshot overview, check out the table below: 

Engine/Generation	Fuel Requirement
First Generation Audi A8 (1994-2002)
2.8L V6, 3.7L V8 and 4.2L V8 Gasoline Engines	Recommended: 91 Octane, Acceptable: 87 Octane
Second Generation Audi A8 (2002-2009)
4.2L FSI V8 and 6.0L W12 Gasoline Engines	Recommended: 91 Octane, Acceptable: 87 Octane
3.0L TDI V6 and 4.0L TDI V8 Diesel Engines	Ultra-Low Sulfur Diesel (ULSD)
Third Generation Audi A8 (2010-2017)
3.0L TFSI V6 and 4.0L TFSI V8 Gasoline Engines	Recommended: 91 Octane
6.3L FSI W12 Gasoline Engines	Recommended: 91 Octane
3.0L TDI V6 and 4.2L TDI V8 Diesel Engines	Ultra-Low Sulfur Diesel (ULSD)
MHEV (Mild Hybrid Electric Vehicle) System	Based on Engine Type – Premium (91 Octane) or ULSD
Fourth Generation Audi A8 (2018-Present)
3.0L TFSI V6 and 4.0L TFSI V8 Gasoline Engines	Recommended: 91 Octane
3.0L TDI V6 Diesel Engine	Ultra-Low Sulfur Diesel (ULSD)
MHEV (Mild Hybrid Electric Vehicle) System	Based on Engine Type – Premium (91 Octane) or ULSD

First Generation Audi A8 (1994-2002)

The inaugural edition of the Audi A8 primarily featured 2.8L V6, 3.7L V8, and 4.2L V8 gasoline engines.

2.8L V6, 3.7L V8 and 4.2L V8 Gasoline Engines

For Audi’s A8, both the 2.8L V6 and the more powerful 4.2L V8 engines were optimally designed for 91 octane.

Most Audi vehicles, including the A8, are designed for premium performance and premium fuel is a part of that. I mean, just listen to the exhaust on that 4.2L and try to tell me you want to put 87 octane in there? 

 

To clarify, while 91 octane is recommended, and that’s the exact phrasing the owner’s manual uses. If that’s not available, you can use 87 octane but you should expect a drop in performance. 

Second Generation Audi A8 (2002-2009)

The second generation A8s said goodbye to anything below 4.2L, but they still all used premium. Expect, of course, the diesel variations that were introduced in this generation. 

4.2L FSI V8 and 6.0L W12 Gasoline Engines

Premium fuel is recommended, but as with the first generation, you can use 87 octane in a pinch. 

3.0L TDI V6 and 4.0L TDI V8 Diesel Engines

The 3.0L and 4.2L TDI engines found in the A8 were a leap for Audi into the world of diesel. These engines require ultra-low sulfur diesel (ULSD), deviating from traditional diesel fuels with higher sulfur contents. Adhering to ULSD not only ensures the TDI engines meet emission standards but also maintains their efficiency.

These variants are less common in US markets. 

Third Generation Audi A8 (2010-2017)

The third generation saw more diversification in engine types, with hybrid versions making their entrance. However, for everything except diesel engines 91 octane is still the recommended fuel. 

3.0L TFSI V6 and 4.0L TFSI V8 

Audi’s TFSI (Turbocharged Fuel Stratified Injection) engines are known for their blend of performance and efficiency. Both the 3.0L V6 and 4.0L V8 fall under this category, using a combination of turbocharging and direct injection to maximize power output and reduce fuel consumption.

This actually is an advanced system (not just marketing hype), which is why a higher octane fuel is recommended. You can learn more about why TFSI engines are a step up (at least compared to what was around at the time) in this video: 

6.3L FSI W12 Gasoline Engines

The 6.3L FSI W12 is a naturally aspirated engine, which means it doesn’t rely on turbochargers or superchargers- unlike other A8s in the third generation. 

However, the W12’s configuration, which aligns 12 cylinders in a compact space, demands a precise burn (AKA premium fuel) for optimal performance. Any inconsistencies in combustion can lead to reduced performance, increased wear, and other potential issues.

You’re also going to miss out on this (and why would you want to do that?): 

All engines within the third and every, generation of the A8 are designed for premium fuel (91 octane), including this one. 

3.0L TDI V6 and 4.2L TDI V8 Diesel Engines

The 3.0L TDI V6 and 4.2L TDI V8 are among Audi’s responses to the demand for diesel engines, which are much more popular in Europe compared to the US. 

Utilizing turbocharging, both engines benefit from increased torque, while the direct injection process helps to optimize fuel efficiency and minimize emissions. Given their design, these engines specifically require ultra-low sulfur diesel (ULSD) to function optimally. Using diesel with higher sulfur content can compromise the engine’s performance and potentially lead to long-term issues.

So while there might be some room to use 87 octane instead of premium fuel in gasoline engines, there’s no space for anything besides ULSD when it comes to the A8’s diesel engines. 

MHEV (Mild Hybrid Electric Vehicle) System:

The third generation A8 also introduced the MHEV or mild hybrid electric vehicle system. Even though “hybrid” is in the name, this feature doesn’t change anything about the engine, or fuel requirements, of the A8. Instead, this system assists the engine anytime there’s enough energy in the battery. 

That means fuel requirements will remain the same for any Audi A8 with this mild hybrid system in place. 

Fourth Generation Audi A8 (2018-Present)

Introduced in 2017 for the 2018 model year, the fourth generation Audi A8 encapsulates Audi’s modernized approach to luxury and efficiency. The primary engine variants have, by now, evolved significantly both in terms of power delivery and their environmental footprint. Here’s a closer look at what’s under the hood and what it means for your fuel choices.

3.0L TFSI V6 and 4.0L TFSI V8 Gasoline Engines:

As with its predecessors, these engine continues to employ turbocharging (thanks to the TFSI system) for a more responsive throttle and improved efficiency. Given its precise engineering, using a 91 octane premium fuel ensures that the engine performs optimally and the turbocharger remains in good health.

On the other hand, opting for 87 octane might not be disastrous, but there’s a high likelihood of not harnessing the engine’s full potential.

3.0L TDI V6 Diesel Engine:

This engine, like its predecessors, demands ultra-low sulfur diesel (ULSD). Using traditional diesel could hinder performance and possibly cause long-term engine issues.

MHEV (Mild Hybrid Electric Vehicle) System:

As before, this doesn’t change the A8’s core fuel requirements. It’s an assistive technology, not a transformative one. So stick with the same fuel requirements based on your engine type- either premium or ULSD.

Does The Audi A8 Require Premium Fuel?

The Audi A8 owner’s manual recommends premium fuel with a minimum octane rating of 91 for best performance. However, the owner’s manual also explains that if premium fuel isn’t available, then 87 octane can work but with some reduction in performance. So the A8 doesn’t require premium fuel but to get the most out of this vehicle you should be using it whenever possible. 

Audi only suggests using 87 octane if premium isn’t available. 

What Are The Fuel Requirements For The A8 MHEV or Hybrid Types? 

Mild Hybrid Electric Vehicle systems only support the drivetrain of the A8 and don’t change anything about how fuel is used or the type needed. In other words, you A8’s engine is the same and the MHEV system just gives it a little help. That means you’ll stick with premium 91 octane and only use 87 octane in a pinch. Diesel engines will stick with ultra-low sulfur diesel. 

Can I Use E85 In My Audi A8? 

There isn’t a single A8 owner’s manual that suggests this is a good idea. E85 is an ethanol-based fuel with up to 85% ethanol content, which is counter to the A8’s recommendation for premium gasoline and a typical limit of up to 10% ethanol.

What Types of Fuels Can and Can’t Be Used in the Audi A8?

Let’s dive into what you can and can’t pour into your Audi A8’s tank. You can read more about each one or just refer to this chart for a quick answer: 

Type of Fuel	Details
Gasoline With Added Materials	Recommended: TOP TIER Detergent Gasoline.
Gasoline With MMT	Avoid: Metal additives can harm the catalytic converter and void warranty.
Gasoline with Alcohol or MTBE	Permissible if AKI ≥ 87 and MTBE ≤ 15%.
Methanol Blends	Allowed: AKI ≥ 87, Methanol ≤ 3%, co-solvents > 2%.
Ethanol Blends	Safe if AKI ≥ 87 and Ethanol ≤ 15%.
Flex Fuels	Avoid: Exceeds 15% ethanol limit.
Biodiesel	For A8 L TDI: B5 is the standard, but B20 is permissible in Illinois.
Reformulated Gasoline	Allowed: AKI ≥ 87 and ethanol ≤ 15%.

Gasoline With Added Materials

In the owner’s manual, Audi suggests using TOP TIER Detergent Gasoline for the A8. This is in line with dozens of other auto manufacturers but there’s plenty of data supporting TOP TIER detergent gasoline it’s impact on your engine. 

Gasoline With MMT

Gasoline with an additive called MMT, or Methylcyclopentadienyl Manganese Tricarbonyl, can be bad news for modern vehicles like the A8 since any metal additive can harm the catalytic converter. The A8 owner’s manual may not specifically say “MMT”, but it does give a heads-up about gas with metal additives. Not only can you expect some damage to your vehicle but you’ll void your warranty as well. Definitely skip it. 

Gasoline with Alcohol or MTBE

The A8 can use gas with MTBE if it has an AKI of 87 or more and doesn’t have more than 15% MTBE.

Methanol Blends

Your A8 can handle gas mixed with methanol but there are some rules. The Anti-Knock Index (AKI) must be at least 87, the blend should have no more than 3% methanol, and it should have over 2% co-solvents.

Ethanol Blends

Gas with ethanol is okay, but make sure it has an AKI of 87 or higher and no more than 15% ethanol, per the owner’s manual. Anything more than that and you’ll run into problems. 

Flex Fuels

Fuels like E20, E30, and E85 have too much ethanol for the A8. Remember, the owner’s manual says no more than 15% ethanol, so steer clear of these.

Biodiesel

The Audi A8 L TDI is only certified to run B5 unless you live in Illinois where it can be run on B20. I know that’s a little strange but it’s a result of varied emissions regulations. So enjoy your B20 in Illinois…but don’t cross state lines!

Reformulated Gasoline

Audi generally maintains that as long as the fuel meets the cars octane requirements and doesn’t contain prohibited additives, it should be compatible. With the A8, reformulated gasoline with up to 15% ethanol is acceptable, given it has an Anti-Knock Index of at least 87 AKI.

Does The Audi A8 Get Good Gas Mileage?

When it comes to luxury vehicles, amazing gas mileage isn’t typically the main draw. The A8 does fare better in the fuel economy department than, say, an SUV like the Q8.

However, when juxtaposed with its luxury peers, it doesn’t exactly lead the pack.

The modern A8 boasts figures of around 19 mpg in the city and 29 mpg on the highway, per the EPA’s data. Of course, it’s the real-world data that really matters and this is probably the most exciting fuel test video I’ve ever seen: 

Gas Mileage Comparison: Audi A8 vs. Other Luxury Models

While 19 city mpg may not make headlines, how does the A8 stack up against the competition?

Looking at the BMW 5 Series, which is in a similar class, its fuel economy measures up at 20 mpg in the city and 28 mpg on the highway. These minor differences might seem trivial, but they could add up in the long run when you think about fuel expenses.

On the other hand, the Mercedes-Benz S-Class, often regarded as the gold standard in luxury (despite its occasional quirks), posts around 20 mpg for city drives and 29 mpg on highways.

In the grand scheme of things, these minor variations might not sway your decision- especially if you’re already in the market for a luxury vehicle. 

Closing Thoughts

For the Audi A8 across its generations, opt for premium 91 octane to keep your A8 running at its prime and prevent problems. In a pinch, 87 octane will work, but you should expect a drop in performance. From my experience, this difference really is noticeable, especially if you’re a little heavy on the gas pedal. 

Ride safe!