Bad gas mileage on new 2019 Optima S

[Progman64]

I am the owner of a brand new 2019 Kia Optima S 2.4 lt. I'm getting less than 300 miles to a full tank of gas and 90 percent of my driving is done on the highway and 10 in the city. I have had the car 6 weeks now with less than 5500 Miles on it. I have gone to the Kia dealership I bout the car from and I was told that nothing is wrong with the car cause the check engine light is not on. I live in the San Diego area and The don't know what to do. I called Kia North Americas office they started a ticket complain number for me and I was told somebody would get back to me. 2 weeks pluss and nothing. I'm thinking I got a lemon car. Can somebody she'd some light on the subject.

[JockoT]

New tyres give poor mileage until the sharp edges start to scrub a little. A new car also takes a bit to get the hang off and get the best out of. After a good run let it slow to a stop then get out and check the wheel centres. They should all be cold (Take care, a dragging brake could heat a wheel up and you can burn your hand if not careful).

[trollbait]

Your tires are just starting to break in. For EPA testing, the tires with the wear of about 4000 miles are used.

Check the tire pressure.

Is the air conditioner being used?

[LDB]

When you take off from a dead stop what rpm do you reach before it shifts to the next gear? What speed on the highway? Stop and go traffic some/most of the way? What tire pressure all around? Oil checked and at the correct level? Passengers in the car? Junk in the trunk or back seat? Any extra weight has a negative effect on mpg. 900 miles a week is a lot of driving and if it's pretty fast that's going to reduce mpg. I think the EPA estimates are done at 55-60mph or something not totally realistic.

[Airstreamer67]

In order to judge fuel economy, one should first determine the miles-per-gallon achieved by the car. This is done by dividing the number of miles driven by the number of gallons used. Then, in an effort to determine whether the car is performing as it should, one can compare the MPG results against the EPA ratings. If the results are significantly different, this could mean that something is wrong, whether it is with the car, the driving technique, etc.

Using a miles-per-tank factor is not a good way to determine efficiency, since the amount of fuel actually used is uncertain due to the uncertainty of how close to absolute empty the tank actually is and thus how many gallons were actually burned.

[JockoT]

Progman64 has never even bothered to enter any info into Fuelly.