2018 Kia Optima S: MPG and fuel economy
The 2018 Kia Optima S is rated by the U.S. Environmental Protection Agency at 26 combined MPG, with 23 MPG in the city and 32 MPG on the highway. That is right around the average car in the Large Cars class for the same model year.
This page collects every fuel-economy figure the EPA publishes for the 2018 Kia Optima S. Below you will find the headline combined, city, and highway MPG, the estimated annual fuel cost at three different driving levels, the tailpipe CO₂ emissions, and a full breakdown of the engine and drivetrain.
Key takeaways
- The most efficient car in the Large Cars class for the 2018 model year is the Tesla Model S 75D at 103 MPG.
Fuel economy at a glance
These are the EPA's official ratings for the 2018 Kia Optima S. The numbers come from a standardised laboratory test cycle and are the same figures that appear on the window sticker of every new car. Real-world mileage varies with driving style, weather, fuel quality, and how heavily loaded the car is.
Combined MPG is a 55/45 weighted blend of the city and highway test cycles. The EPA uses it as the single number you can compare across the entire dataset, including hybrids and EVs (which use the equivalent MPGe figure).
| Combined MPG | 26 MPG |
| City MPG | 23 MPG |
| Highway MPG | 32 MPG |
| Annual fuel cost | $2,300 |
| Tailpipe CO₂ | 340 g/mi |
| Fuel type | Regular |
How the 2018 Kia Optima S compares
The 2018 Kia Optima S returns 26 combined MPG. Cars in the Large Cars class for the same model year average 26.5 MPG, which puts this car behind the class average by about 2%.
The most efficient car in the Large Cars class for the 2018 model year is the Tesla Model S 75D at 103 MPG. The bar chart below puts the Kia Optima S alongside the class best and the class average so you can see the full picture.
For broader context, the average new car of the 2018 model year (across all classes) returns 25.6 MPG. Larger vehicles pull the all-cars average down, so do not use that figure on its own to judge a small car or a hybrid. The full list of the most efficient cars of the 2018 model year is on its own page.
Annual fuel cost across driving patterns
The headline annual fuel cost the EPA publishes assumes 15,000 miles of driving per year and a fuel mix of 55% city and 45% highway. The dollar figure is calculated using the EPA's current reference price for regular gasoline, which is $3.99/gallon. EPA updates that reference periodically rather than tracking live pump prices, so treat it as a window-sticker estimate rather than today's pump number.
The table below scales the EPA's number to three common driving patterns. The combined MPG and the reference fuel price stay constant, only the annual mileage changes. To get a current-prices estimate, take your local gas price and multiply by 576.9 gallons (the car's annual consumption at the rated MPG).
| Driving pattern | Estimated annual fuel cost |
|---|---|
| Light driver, 7,500 miles per year | $1,150 |
| Average driver, 15,000 miles per year | $2,300 |
| Heavy driver, 25,000 miles per year | $3,833 |
Compare against other Large Cars for 2018
If you are cross-shopping the 2018 Kia Optima S, the most useful comparison is against the other cars in the Large Cars class for the same model year. The list below shows the highest-MPG peers, ranked from most to least efficient. Click any of them to open its full page.
The Tesla Model S 75D leads this group at 103 MPG, 77 MPG ahead of the 2018 Kia Optima S.
Specifications
The 2018 Kia Optima S runs a 2.4-liter 4-cylinder engine paired with a automatic (s6), sending power through front-wheel drive.
Engine, transmission, and drivetrain together drive most of the variation in fuel economy across trims. A larger engine moves the car with less effort but burns more fuel. A turbo lets a small engine punch above its weight, often without much MPG penalty. All-wheel drive adds traction and weight, and usually costs a couple of MPG compared with two-wheel drive of the same engine.
- Vehicle class
- Large Cars
- Engine
- 2.4L 4-cylinder
- Transmission
- Automatic (S6)
- Drivetrain
- Front-Wheel Drive
- Fuel type
- Regular
- Annual petroleum use
- 11.4 barrels per year
Common questions about the 2018 Kia Optima S
Quick answers to the questions people most often search for when looking up the 2018 Kia Optima S.
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Is the 2018 Kia Optima S fuel efficient?
It is in line with the rest of the class. The 2018 Kia Optima S returns 26 combined MPG, and the average car in the Large Cars class for the same model year sits at 26.5 MPG. -
What MPG does the 2018 Kia Optima S get?
The EPA rates the 2018 Kia Optima S at 26 combined MPG, 23 MPG in city driving, and 32 MPG on the highway. Real-world numbers depend on your driving style, the weather, and how loaded the car is. -
How much does it cost to fuel a 2018 Kia Optima S per year?
The EPA estimates an annual fuel cost of $2,300 for the 2018 Kia Optima S. That figure assumes 15,000 miles of driving per year, a 55% city and 45% highway split, and the EPA's published average fuel price for the rated fuel grade. -
What fuel does the 2018 Kia Optima S use?
The EPA lists the 2018 Kia Optima S as running on regular gasoline. Using a different grade than the manufacturer specifies can affect fuel economy and engine longevity. -
How much CO₂ does the 2018 Kia Optima S emit?
Tailpipe CO₂ emissions are 340 g/mi. Multiplied across a typical year of driving (15,000 miles) that works out to about 5,100 kilograms of CO₂. -
What is the difference between the city and highway MPG of the 2018 Kia Optima S?
City driving returns 23 MPG and highway driving returns 32 MPG, a gap of 9 MPG. A spread that wide is typical of cars with conventional automatic or manual transmissions, where stop-start city traffic eats more fuel than a steady highway cruise. -
What engine is in the 2018 Kia Optima S?
The 2018 Kia Optima S has a 2.4-liter 4-cylinder engine (EPA description: SIDI). -
What transmission and drivetrain does the 2018 Kia Optima S have?
The 2018 Kia Optima S comes with a automatic (s6) transmission and front-wheel drive. -
How does the 2018 Kia Optima S compare to the best car in its class?
The most efficient car in the Large Cars class for the 2018 model year is the Tesla Model S 75D at 103 combined MPG. The Kia Optima S returns 26 MPG, a gap of 77 MPG. If you are comparing on fuel economy alone, the class leader is worth a look. -
How much petroleum does the 2018 Kia Optima S use per year?
The EPA estimates the 2018 Kia Optima S consumes about 11.4 barrels of petroleum per year, based on the standard 15,000 miles of driving. A barrel is 42 U.S. gallons of crude oil, which is refined into gasoline plus other products.
Source: U.S. EPA fuel economy dataset. Annual fuel cost figures assume 15,000 miles of driving per year and a 55% city, 45% highway split. Real-world mileage varies with driving conditions, vehicle maintenance, fuel quality, and driver behaviour.