This blog will discuss the BMW 5 Series’ fuel-related characteristics and specifications, such as the type of engines and the recommended fuel types each requires. On top of that, we will be looking at the other fuel types that can and cannot be used, the highway, city, and combined mileage per gallon, the size of the fuel tank, and what it would cost today to fill up your BMW.
All generations of the BMW 5-series require premium unleaded gasoline with an octane rating of 91 or higher. This type of gasoline is also recommended for the hybrid engines manufactured since 2018. For 5-series with a diesel engine, ultra-low sulfur diesel is recommended.
This is consistent with other BMW models like the X6 or series 3. Now let’s look at all the available engine options in detail and see what gas each engine will run on. Note that a wrong fuel type can cause engine damage, and prolonged use of a non-recommended fuel type will lead to irreparable damage, and therefore your engine will fail prematurely.
So fasten your seatbelts because it is going to be a serious ride.
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Fuel Requirements Based On Engine Type
The following table summarizes the various engines and the fuel types recommended for each case. For gas engines, the recommended fuel is premium unleaded gas with an AKI of 93. For diesel engines, the diesel should have ultra-low sulfur content.
| Engine | Year | Fuel Type |
| 2.0 L | 2012-2022 | Premium unleaded gas |
| 2.0 L | 2018-2022 | Electric/Hybrid: Premium unleaded gas |
| 2.5 L | 2003-2005 | Premium unleaded gas |
| 3.0 L | 2003-2022 | Premium unleaded gas |
| 3.0 L | 2014-16 & 2018 | Ultra-low sulfur diesel |
| 4.4 L | 2003-05 & 2010-16 | Premium unleaded gas |
| 4.8 L | 2006-2010 | Premium unleaded gas |
Also read: How Many Miles Can A BMW 5 Series Last? (Answered)
What Types Of Gasoline Can And Can’t Be Used?
There was either gas or diesel back in the good old days. There was not much to choose from or worry about. We now have a wide variety of fuels, and then we have grades within each type of fuel. Similarly, engines are now designed specifically for a particular fuel type, and therefore car owners need to be aware of the recommended fuel for their car.
Most modern gas engines are either based on unleaded gas or premium unleaded gas. The various types of gas are graded by their AKI (Anti Knock Index) number. Diesel is rated according to ASTM number. The new fuel types have their rating methodology; for example, those based on ethanol are rated as E followed by a number.
Reformulated Gasoline
Reformulated Gasoline is conventional gasoline that came into being to meet specific requirements. The most important was the need to lower harmful emissions by reducing smog-causing agents. The 1990 Clean Air Act passed by Congress mandated the RFG program. It has significantly helped to bring down smog levels across the USA.
There are general recommendations in the 5 Series owner’s manual, which state that the gas that can be used must be sulfur-free or low in sulfur content. The recommended minimum fuel grade can be AKI 91, but it is desirable to use premium unleaded gasoline with AKI 93.
Based on the above recommendations, any reformulated gasoline that meets these requirements can be used in BMW 5 Series.
Gasoline/Oxygenated Blends Or E-85
Fossil fuels are hydrocarbons composed of hydrogen and carbon atoms. Oxygenates are a family of hydrocarbons that contain one or more oxygen atoms.
Oxygenates have been blended in gas to increase their octane rating and burn more cleanly, reducing the pollution caused by the toxic carbon monoxide. Another reason for using oxygenates is their blending properties in motor gasoline. The most commonly used octane enhancing oxygenates are alcohol and ethers.
With a renewed emphasis on reducing environmental pollution caused by fossil fuels, about one-third of all gas sold in the USA is oxygenated with 10% ethanol. Such fuels are designated by “E” followed by the ethanol content percentage. E10 is an oxygenated blend with 10% ethanol. BMW allows ethanol blending as long as it is no more than 10%.
Flex-fuel or E85 is one of the most popular oxygenated blends. It consists of 85% ethanol, and owing to its popularity; some car manufacturers have designed engines that run on Flex-fuel and conventional gasoline. However, BMW does not allow the use of the E85 because of its harmful effects on the engine and the damage to the fuel supply system.
Gasoline With Added Materials
To attract more consumer attention and increase their sales, gasoline manufacturers add materials to gas that act as octane enhancers and function as lubricants, detergents, and anti-corrosives.
Additives are various types, including oxygenates, dyes, antioxidants, antiknock agents, ethers, etc. Oxygenates are mostly octane enhancers; antiknock agents reduce engine knock and increase octane rating, while antioxidants act as stabilizers.
For all of their advertised qualities, however, there are a lot of doubts about whether additives work or not. According to a study conducted by EPA in 2011 of more than 100 additives, none delivered what was claimed.
However, some additives work as gunk cleaners and prevent the buildup of gunk, which can clog fuel injectors. In older cars, additives are more likely to improve engine performance because older vehicles have more gunk deposits in fuel injectors. However, if your car is new and running without any issues, it is recommended not to use additives.
BMW allows the use of fuel with additives if it is purchased from TopTier or Shell. BMW prohibits alcohols, such as methanol, and metal additives, such as iron and manganese, as these can cause damage to the catalytic convertor.
Failure to follow recommendations as outlined by BMW may require unscheduled maintenance.
Gasoline With MMT (Methylcyclopentadienyl manganese tricarbonyl)
MMT, an octane enhancer, is one of the most controversial gasoline additives. Depending on which side you are on, it is either the best fuel additive that considerably enhances engine performance with no environmental impact or impairs engine performance and is the worst enemy of the environment and public health.
In a nutshell, MMT is for racing, but both eyebrows are raised when it comes to its effect on engine life. Auto manufacturers are generally opposed to its use, and not surprisingly, BMW does not recommend the use of gasoline formulated with MMT.
Biodiesel
Biodiesel is a biodegradable fuel sourced from animal fats and fatty acids found in vegetable oils. Biodiesel is compatible with conventional diesel engines and fuel distribution systems. However, most engines cannot operate on pure biodiesel and require blending with petro-diesel.
The general recommendation for diesel engines in the USA is ASTM D975 which has ultra-low sulfur content. B5 is a biodiesel blend compatible with the ASTM D975, so there is no need for separate labeling at the pump. BMW recommends using ASTM D975 ultra-low sulfur diesel and biodiesel with a concentration up to B5.
In summary, BMW’s recommendation for gas engines is to use premium unleaded gas with an AKI, preferably 93. However, gas with an AKI of 91 can also be used without engine damage. For diesel engines, the recommendation is ASTM D975 ultra-low sulfur diesel.
What If I Hear A Knocking Noise From The Engine After Refilling?
What is engine knock? Engine knock happens when the air and gas mixture is not entirely consumed at the first detonation, and subsequently, there are smaller ignitions. These subsequent detonations are what cause engine knock.
For optimal performance, it is necessary to use the recommended fuel type. Gas is rated by its octane rating. A higher octane rating means that the air and fuel mixture can be compressed to a lower volume (higher compression ratio), which releases greater heat energy at detonation and converts it into mechanical energy to drive the car.
There is no need to worry if the knock results from using a fuel with a lower octane rating than recommended. Simply filling up the next few tanks with premium fuel should ease the problem. If the engine continues to knock, it is necessary to have the car checked by a BMW authorized technician.
Does The BMW 5 Series Have Good Gas Mileage?
In this section, we will look at the fuel efficiency of the various 5 Series generations, starting with the 5th generation. BMW used four engine variants for the fifth generation (2003-10). All were based on premium unleaded fuel. Surprisingly the 3.0 L engine outperformed the 2.5 L engine despite its somewhat bigger size.
| Engine | Combined (city/hwy) MPG | City MPG | Highway MPG |
| 2.5 L 6 Cyl | 20 | 17 | 26 |
| 3.0 L 6 Cyl | 21 | 18 | 27 |
| 4.4 L 8 Cyl | 18 | 15 | 23 |
| 4.8 L 8 Cyl | 18 | 15 | 23 |
The sixth generation of 5 Series spanned from 2004 to 2017. The most widely used engines in this generation were 3.0 L and 4.4 L. The 4.8 L engine was discontinued. However, a diesel engine was introduced.
| Engine | Combined (city/hwy) MPG | City MPG | Highway MPG |
| 2.0 L 6 Cyl | 26 | 23 | 33 |
| 3.0 L 6 Cyl | 23 | 20 | 29 |
| 3.0 L 6 Cyl (diesel) | 30 | 26 | 37 |
| 4.4 L 8 Cyl | 19 | 16 | 24 |
The seventh and the current generation was announced in 2016, with sales starting in 2017. The diesel engine was discontinued in 2017 but reintroduced one year later and then discontinued again. The 4.4 L engine was discontinued after 2017, and only 2.0 L and 3.0 L engines have been used since. The electric-gas hybrid was introduced in 2018.
| Engine | Combined (city/hwy) MPG | City MPG | Highway MPG |
| 2.0 L 6 Cyl | 27 | 24 | 34 |
| 3.0 L 6 Cyl | 25 | 22 | 30 |
| 3.0 L 6 Cyl (diesel) | 30 | 26 | 36 |
| 4.4 L 8 Cyl | 18 | 15 | 24 |
| Engine | Combined (city/hwy) Elec-Gas combined | Combined (city/hwy) Premium Gas |
| 2.0 L 6 Cyl (Hybrid) | 63 | 26 |
What’s The Gas Tank Size Of A BMW 5 Series?
The table below shows the Series 5 gas tank size since 2004. Unlike the 3 Series, the tank size of the 5 Series has not seen too many changes, hovering between 18.0 gallons and 18.5 gallons, with a few exceptions.
| Engine | Type | Year | Gas Tank (gallons) |
| 2.0 L/3.0 L | Gas | 2004,2007-2017 | 18.5 |
| 3.0 L | Diesel | 2014-2016 | 18.5 |
| 2.0 L/3.0 L | Gas | 2005-2006, 2017-2022 | 18.0 |
| 3.0 L | Gas | 2015-2017 | 17.7 |
| 3.0 L | Diesel | 2018 | 17.4 |
How Much Does It Cost To Fill Up A BMW 5 Series?
The previous section provided details about BMW 5 Series tank sizes. Using this same table, we can estimate how much it would cost to fill these tanks, given the current gas prices. We have used the average gas/diesel price currently in the USA to do these calculations.
| Gas Tank (gallons) | Type | Average cost per gallon ($) | Cost to fill the tank ($) |
| 18.5 | Gas | 4.851 | 89.74 |
| 18.5 | Diesel | 5.296 | 97.98 |
| 18.0 | Gas | 4.851 | 87.32 |
| 17.7 | Gas | 4.851 | 85.86 |
| 17.4 | Diesel | 5.296 | 92.15 |
Some states, such as California, Washington, Alaska, etc., have higher than average fuel prices. For example, in California, the current price for premium unleaded fuel is about $1.25 higher than the national average. At the same time, it is about 30 cents cheaper in Texas on the other side of the spectrum. So the cost of getting a full tank will vary from state to state.
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Hi! My name is Stefan; I’m the owner and lead writer at TheDriverAdviser.com.
I’m an active writer on this blog myself, as well as a novice car mechanic. For the really technical stuff, I find writers with experience as a mechanic or who have studied mechanical engineering.
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