Types Of Gas A BMW 3-Series Takes (Explained)

We are back with another gas-related blog, and this time we are taking a look at the BMW 3 Series. In this blog, starting with the fifth-generation (2004) and onwards, we will share fuel-related information for Series 3, such as the BMW recommended fuel types, which kinds of fuels to avoid, its fuel economy, and the tank size. So what gas does a 3-series take? Well, the short answer is below.

BMW 3-series manufactured from 2004 onwards take premium unleaded gasoline with an octane rating of 91, this is also the recommendation for the hybrid versions. 3-series that have a diesel engine use ultra-low sulfur content with an ASTM D975 rating.

This shouldn’t be a surprise to experienced BMW owners and we see similar premium fuel requirements in vehicles like the X6 and 5-series.

However, that certainly doesn’t tell the full story. Below, we’ll dive deeper into the types of gasoline that are preferred for each generation of the 3-Series. We’ll also discuss other related aspects such as fuel tank size and mileage. Read on!

If you want to learn more about a specific model consider checking the BMW 330e common problems, or browse for more BMW-related articles.

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Fuel Requirements Based On Engine Type

The following table gives a quick overview of the different types of engines used in the 3 Series, the model years, and the recommended fuel for each engine type.

Engine (Year)	Fuel Requirement
2.0 L (2012-22)	Premium unleaded gas 91 AKI
2.0 L (2014-18)	Ultra-low sulfur diesel
2.0 L (2016-18, 21,22)	Electric/Hybrid: Premium unleaded gas 91 AKI
2.5 L  (2004-06)	Premium unleaded gas 91 AKI
3.0 L (2004-19)	Premium unleaded gas 91 AKI
3.0 L (2009-11)	Ultra-low sulfur diesel

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

An important thing to know is that not all gas is the same. And with all the different types of gas currently available, it is essential to know which ones can be used and which ones can cause damage to your car engine.

The general recommendation for gas engines is to use unleaded gas with an Anti-Knock Index (AKI) of 91. However, based on the model, the minimum rating can be 87 AKI or 89 AKI. There is nothing to worry about if the engine produces knocking sounds when starting at high outside temperatures. The recommendation for diesel is ultra-low sulfur diesel with a rating of ASTM D 975-07a. 

In the rest of this section, we will analyze the major categories of gas and share BMW’s recommendation on whether it is safe to use in Series 3.

Reformulated Gasoline

Reformulated gasoline (RFG) is one of the many newer types of fuels that have become popular because of the general awareness of reducing air pollutants produced by burning fossil fuels. 

As the name suggests, reformulated gasoline is a gasoline blend with lower sulfur content. Sulfur is one of the major smog-producing ingredients in fossil fuels. RFG has lower sulfur content and burns more cleanly. Its use has helped reduce smog and is now mandatory across many cities in the USA. 

As per the BMW owner’s manual, the general recommendation is that fuel should be sulfur-free or low in sulfur content and have an octane rating, depending upon the engine, between 87 and 91. RFG that meets this criterion can be used in BMW 3 series.

Gasoline/Oxygenated Blends Or E-85

Oxygenates are compounds with oxygen molecules in their molecular structure. Oxygenates, such as ethanol and natural gas, are used as additives to increase their oxygen. The idea is twofold; it is a cheap way to increase the octane rating and decreases exhaust emission.

With the emphasis on reducing the carbon content in the environment, a very high percentage of gas sold in the USA has been oxygenated with 10% ethanol. This fuel is generally marked as E10, and BMW allows the use of oxygenated gas that has no more than 10% ethanol as its content.

One of the more popular oxygenated blends is E85 or Flex Fuel which consists of 85% ethanol. Some car manufacturers have come up with engines designed to run on Flex Fuel and regular gasoline. BMW prohibits the use of E85 because its use can have detrimental effects on the engine and the fuel supply system.

Gasoline With Added Materials

An engine is composed of many moving parts grinding against each other, generally at very high temperatures. Engines need to be well lubricated to minimize wear and tear. Materials are added to gasoline to increase its octane rating and act as a lubricant, detergent, or anti-corrosive. 

While there are still questions about the performance enhancement qualities of gas additives, some additives can act as lubricants and help keep the moving parts of the engine in good shape. However, the general recommendation is that if your car is in good running condition, using gasoline with additives is not advisable.

BMW recommends buying fuel with additives if purchased from TopTier or Shell brands. Only ethanol is safe to use among alcohols if it is no more than 10% of the content. BMW prohibits the use of methanol. Metal additives such as iron and manganese are also prohibited as these can cause permanent damage to the catalytic convertor.

Additionally, BMW warns that failure to follow recommendations outlined in the owner’s manual may require unscheduled maintenance.

Gasoline With MMT

MMT or Methylcyclopentadienyl manganese tricarbonyl is an additive that is a type of chemical used as an octane enhancer. However, its benefits seem to be outweighed by the problems that it might cause to the environment. And not to mention the damage it causes to the engine internals.

Studies conducted on MMT use have shown that its use may cause increased hydrocarbon emission, which alone should be a reason for not using it. Public health officials are against its usage because of potential health hazards. It has also been shown to cause increased spark plug deposits and plugging of monolithic converters.

BMW prohibits the use of gasoline that has been reformulated with MMT.

Biodiesel

For its diesel engines, BMW recommends using ultra-low sulfur diesel (ULSD). Besides conventional petro-diesel, other types of diesel are available in the market. The most popular of these is biodiesel. It is a biodegradable fuel based on vegetable oils, animal fats, or recycled restaurant grease. 

Biodiesel is blended in different concentrations, with the most common being B5. In the case of conventional diesel, the recommended grade is ASTM D975. This specification allows for biodiesel with a concentration up to B5. In terms of standard, biodiesel B5 is like petro-diesel fuel with no separate labeling needed at the pump.

BMW allows biodiesel with concentration levels up to B5 for its diesel engines.

To summarize, for gas engines, BMW’s recommendation is to use premium unleaded gas with an AKI preferably of 93. ASTM D975 ultra-low sulfur diesel is the diesel of choice for diesel engines. The preceding section gives some detail about fuel types and their use, but we recommend that you consult the BMW owner’s manual as well. 

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

Knock is the repetitive tapping or pinging sound when you accelerate the car instead of the smooth rumble of your car.

The most common car engines are four-stroke gasoline engines. These strokes are cycles that the engine goes through to produce the energy to run the car. One of these is the compression stroke, where the air and gas mixture is compressed to a small volume before the spark plug ignites the fuel. The compressed volume of air and gas is called the compression ratio.

Octane rating measures how much gasoline can be compressed before it ignites. This compressed volume burns in small regulated pockets to produce better fuel efficiency. If these pockets burn unevenly, the shocks go off at the wrong time resulting in an engine knock. Higher octane rating fuels are more likely to burn evenly.

So if the knocking results from the use of lower octane gas, then BMW recommends filling up the next couple of tanks with premium fuel to ease the issue. However, if the knocking continues even after using premium fuel, it is necessary to have the car checked by a BMW authorized technician.

Does the BMW 3 Series Have Good Gas Mileage?

Fifth-generation (2004-2010)

The fifth-generation BMW used 2.5 L and 3.0 L engines to power the 3 Series. The 2.5 L was discontinued after 2006, whereas starting in 2009, BMW introduced a 3.0 L diesel engine. The average gas mileage for these engines is given in the table below.

Engine/Type	Highway MPG	City MPG	Combined MPG
2.5 L/Premium gas	25	17	20
3.0 L/Premium gas	25	17	20
3.0 L/Diesel	36	23	27

Sixth-generation (2011-2017)

BMW added a 2.0 L premium gas engine and a diesel engine for the sixth generation to go along with the 3.0 L engine already in use. A 2.0 L electric-gas hybrid engine was introduced in 2016.

Engine/Type	Highway MPG	City MPG	Combined MPG
2.0 L/Premium gas	33	23	27
2.0 L/Diesel	41	31	34
3.0 L/Premium gas	28	18	22
3.0 L/Diesel	36	23	27

Engine/Type	Gas-Electric Combined MPG	Gas Combined MPG
2.0 L/Gas-Electric Hybrid	71	30

 Seventh-generation (2018-Present)

BMW continued using 2.0 L and 3.0 L engines for the seventh-generation. However, in 2020 it discontinued the 3.0 L engine. There were no hybrid engines for 2019 and 2020, and there have been no diesel engines since 2019. The average fuel economy figures are given below.

Engine/Type	Highway MPG	City MPG	Combined MPG
2.0 L/Premium gas	34	24	27
2.0 L/Diesel	40	30	34
3.0 L/Premium gas	32	21	25

Engine/Type	Gas-Electric Combined MPG	Gas Combined MPG
2.0 L/Gas-Electric Hybrid	71	30

Also read: How Many Miles Can A BMW 3 Series Last? (Answered)

What’s The Gas Tank Size Of The BMW 3 Series?

The following table clearly shows that BMW was not quite sure of what size of the gas tank to use. There were changes almost every year. Between 2012-2019 the tank size has been 15.8 gallons for gas engines and 15.0 gallons for diesel engines.  

Engine/Year	Gas Tank (gallons)
2.0 L & 3.0 L/2004	16.6
2.0 L & 3.0 L/2005	17.0
3.0 L/2006	16.0
3.0 L/2007	15.9
3.0 L/2008-11	16.1
2.0 L/2012-18	15.8
3.0 L/2012-13	16.1
3.0 L/2014-19	15.8
2.0 L(H)/2016-18	10.8
2.0 L(D)/2014-18	15.0
2.0 L/2019-22	15.6
2.0 L(H)/2021-22	10.6

How Much Does It Cost To Fill Up A BMW 3 Series?

Since 2004, gas engines have had a maximum and minimum tank size of 17.0 and 15.6 gallons. With the current cost of premium unleaded fuel at $4.762, it will cost between $80.95 and $74.29 to fill the tank. Similarly, diesel engines’ maximum and minimum tank size has been 16.1 and 15.0 gallons, respectively. 

The current per-gallon cost of diesel is $5.028, so it will cost between $80.95 and $75.42 to fill the tank. The tank size for a hybrid has either been 10.6 or 10.8, and it would cost between $50.48 and $51.43 to fill it.

Sources

• https://en.wikipedia.org/wiki/BMW_3_Series

• https://www.fueleconomy.gov/

• https://www.edmunds.com/

• https://www.autobytel.com/car-ownership/maintenance-repair/what-are-gasoline-additives-104284/

• https://afdc.energy.gov/fuels/biodiesel_basics.html

• https://afdc.energy.gov/fuels/biodiesel_blends.html

• https://gasprices.aaa.com/