I bought this car about a year and a half ago. It used to get around 26 mpg, but now it’s down to 18.9 mpg. The miles-until-empty reading seems way off too. I can lose 30 miles in just one minute of driving. What’s going on?
If you’re mostly doing city driving, especially short trips under 5 miles, it can really hurt mpg. But if you’re driving mostly on the highway and still getting low mpg, you might need to check your spark plugs. My Focus used to get 40 mpg on the highway no problem.
Start with the basics—check your spark plugs and air filter. Also, grab a bottle of Techron fuel system cleaner and pour the whole thing into a full tank of gas. Even if it says it treats more than your tank size, it’s fine to use it all. Let me know how it goes.
How much gas does the car take when it’s empty? You might have a warped fuel tank messing with the fuel level reading. Another possibility is a failing catalytic converter, which can also tank your mpg.
@Spence
From the way OP described the miles-to-empty issue, this might be a bad purge valve.
Does your mpg calculation from the fuel gauge match when you calculate it manually? Sometimes the car’s computer can report weird numbers for no clear reason.
A buddy of mine had the same issue with his Fiesta. Replacing the throttle body made a big difference in mpg.
Finnian said:
A buddy of mine had the same issue with his Fiesta. Replacing the throttle body made a big difference in mpg.
You could try cleaning the throttle body and the Mass Airflow Sensor first. It’s cheap and easy to do.
Is your car automatic or manual? If it’s an automatic, maybe there’s an issue with the transmission.
Devi said:
Is your car automatic or manual? If it’s an automatic, maybe there’s an issue with the transmission.
It’s manual.
Are you driving like you’re in a race? That could kill your mpg fast.
You should double-check your mpg by calculating it manually. Is your check engine light on? Are there any other issues like hesitation or sticking brakes?
I don’t own a Focus anymore, but I recently tuned up my 2016 Kia Rio and got an 8-10 mpg improvement. Maybe these tips will help you too. Here’s what I did:
- Changed transmission oil
- Replaced the air filter and spark plugs
- New serpentine belt
- Oil and filter change
- New tires and alignment
- Got an intake valve cleaning for the GDI engine
- Added a bottle of fuel system cleaner
Hope some of this helps!
@Clove
I used fuel system cleaner too and it really helped my car. I went for the strongest one I could find—something that’s even banned in Europe.
Scout said:
@Clove
I used fuel system cleaner too and it really helped my car. I went for the strongest one I could find—something that’s even banned in Europe.
Which cleaner did you use? I’d love to know for future reference.
@Clove
Redline. Worked great for me.
Your timing belt could be wearing out. When it stretches, it throws off valve timing, which leads to worse mpg. I noticed a big improvement after I replaced mine.
Arin said:
Your timing belt could be wearing out. When it stretches, it throws off valve timing, which leads to worse mpg. I noticed a big improvement after I replaced mine.
I already replaced the engine with a 100k-mile one because the old one had a dead cylinder. I also put in a new clutch and flywheel along with other new parts.
Try accelerating and braking more gently. Anticipate traffic to avoid wasting fuel.