High fuel consumption...Help (2019 Mazda6)

[elfish]

hi my car have very high fuel consumption,
car is 3rd gen mazda ,6
year 2019
auto 2.5 engine,
can carbon build up be the issue or something else, do you think chaing gearbox oil and filter and spark plugs will improve fuel consumption,
15 litre highway way above specs again.
10 litres city - specs 5-6 litres max

car is out of warranty 50k miles so far.

 

[Elrathias]

What rpm at what speeds, and in what gear?

The skyactive-g has no common failure points that lead to excessive fuel consumption, atleast as far as i know.

I know its a pretty old thread, but the petrol engines are amazingly efficient and should be around 39MPG or around 5,9-6,1L/100km

 

[sm1ke]

Driving habits can certainly contribute to a less impressive fuel economy figure. A heavy foot, to be specific. That said, short trips that do not allow the engine to reach operating temp can contribute to early carbon build up. One of the initial symptoms is lower fuel economy and increased engine noise, vibration, and hardness (NVH). Carbon build up can be verified by a mechanic using a boroscope. I believe you can also check it yourself if you have a boroscope, but I'm not familiar with the process.

Outside of that, though, if the spark plugs have never been changed, that's a good place to start. Another would be to start fueling from a station that sells top tier fuel, like Shell, if you aren't already. You can also try a fuel injector cleaner like Redline SI-1. I have also recently started using Marvel Mystery Oil on my last fill up, and so far it seems to have slightly improved my fuel economy.

 

[Snorting2.5]

hi my car have very high fuel consumption,
car is 3rd gen mazda ,6
year 2019
auto 2.5 engine,
can carbon build up be the issue or something else, do you think chaing gearbox oil and filter and spark plugs will improve fuel consumption,
15 litre highway way above specs again.
10 litres city - specs 5-6 litres max

car is out of warranty 50k miles so far.

Your car is getting 15L/100KM in the highway, more than in the city? is this correct?

Can you tell us how you drive? What gears, RPM?