On this blog, we’ve written extensively about the American-made Hyundai Sonata, its capacities and various features. Today we’re going to talk about what fuel this sedan needs and what kind of fuels are strictly prohibited. Please keep in mind that we’ve gone through the owners manuals of all Sonatas that were produced from 2001 onwards. Let’s start with a quick answer:
All generations of the Hyundai Sonata produced from 2001 onwards use regular unleaded gasoline with an octane of 87 or higher. Premium gasoline is not recommended since it does not have any benefits over regular gasoline for the Sonata.
However, that doesn’t tell the full story. Below we’ve outlined recommendations and requirements for different kinds of fuels and fuel additives. Furthermore, we discuss the fuel mileage of all generations manufactured from 2001 onwards and we give an overview of the tank size of these generations. Read on!
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Also read: How Many Miles Can A Hyundai Sonata Last? (Answered)
Let’s start by clarifying a few things about premium gasoline. Many Sonata owners wonder whether or not they should use this kind of fuel in their car. However, it’s not advised to use premium gasoline in Sonata for the simple reason that this has not performance or durability benefit whatsoever.
Only engines that are designed specifically for premium fuel (with an octane level of 91 or higher) should use premium fuel because these engines are able to make use of the higher octane level. For the Sonata you would simply be overpaying for fuel that does not help the car perform better in any way.
Reformulated gasoline is gasoline that burns cleaner and reduces emissions. First introduced in California because of the low air quality in this region, reformulated gasoline has made its way to gas stations around the United States. In some states, reformulated gasoline is required by state law.
Hyundai states that reformulated gasoline is suitable for all generations of the Hyundai Sonata and that it’s even advised to use this kind of fuel whenever it’s available. No extra precautions need to be taken when using this fuel, and no additional maintenance needs to be carried out.
Gasoline With Additives
Adding additives to the fuel of your Hyundai Sonata is generally not recommended. The reason for this is that these additives may contain silicone, ferrocene or metals that will damage the fuel system when used. Furthermore, the damage that is caused is not covered under warranty and major repairs may be needed.
Hyundai generally recommends you use gasoline sold by TOP TIER retailers. The gasoline that these retailers sell already has all the right additives mixed into it for optimal fuel performance and durability of the fuel system and engine. To find TOP TIER retailers you have to go to toptiergas.com.
If a TOP TIER retailer is not available in your region, Hyundai has specific recommendations for the 2009 – 2017 Sonata. It’s recommended that you add one bottle of additive every 7.500 miles or at every oil change. However, these bottles should only be bought at Hyundai dealers because these dealers can tell you the exact additives that should be used. Using a random additive is therefore not recommended.
Gasoline Containing Ethanol/Methanol
Some gasoline contains a blend of regular gasoline and ethanol or methanol. For Hyundai Sonata’s manufactured between 2001 – 2019, Hyundai states that they can use gasoline with a maximum ethanol percentage of 10% (E-10). However, blends with 15% or 85% (E-15 and E-85) are not allowed. For Sonata’s that were manufactured after 2019, a maximum of 15% ethanol is permitted. Furthermore, Sonata’s aren’t designed to use methanol in any way, shape or form.
Using gasoline with a higher than stated ethanol or methanol percentage will be a breach of the warranty. This means any damage that occurs is not covered by Hyundai or any other form of warranty.
What If I Hear Knocking After Refilling?
Hearing a slight knocking sound after refilling is completely normal and nothing to be concerned about. However, if the knocking sound increases in volume and becomes very loud you should immediately stop the car and contact your dealer. It’s very likely your car needs to be drained of the fuel it’s currently using.
This knocking sound is also referred to as ‘spark knock’ and it means the fuel that’s being used is not ignited properly. This is most likely caused because you’ve used a fuel that has an octane rating of 86 or lower. Using this kind of fuel will damage the engine and fuel system and therefore the car needs to be drained.
Also read: 8 Common Problems Of A Hyundai Sonata Hybrid
Fuel Mileage Of The Hyundai Sonata
Besides knowing what kind of fuel you should use it’s of course also important to know what gas mileage you can expect or should get with you Sonata. Below, we’ll discuss the combined, city and highway MPG of different kinds of Sonata.
As expected, the earlier generations of the Sonata do not have that well of a gas mileage. However, the newer versions have a very decent gas mileage and, when you have a hybrid in one way or another, you have a gas mileage that’s phenomenal. Take a look!
|Year||Engine||Combined MPG||City MPG||Highway MPG|
|2001 – 2004||2.4||22||19||28|
|2004 – 2009||2.4||24||21||30|
|2009 – 2014||2.0||26||22||33|
|2014 – 2017||1.6||31||28||36|
|2.0 PHEV||99 (elec+gas)||40 (reg. gas)||–|
|2017 – 2019||1.6||31||28||37|
|2.0 PHEV||99 (elec+gas)||39 (reg. gas)|
|2019 – Present-day||1.6||30||27||37|
|2.0 Hybrid Blue||52||50||54|
Tank Size Per Generation
- The 2001 – 2004 Hyundai Sonata has a tank size of 17.2 gallons.
- The 2004 – 2008 Hyundai Sonata has a tank size of 17.7 gallons.
- The 2009 – 2014 Hyundai Sonata has a tank size of 18.49 gallons (70 liters).
- The 2014 – 2019 Hyundai Sonata has a tank size of 18.5 gallons (70 liters).
- The 2020 – Present-day Hyundai Sonata has a tank size of 15.85 gallons (60 liters) for standard models and 14.79 gallons (56 liters) for the ECO models.
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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