About 2 years ago I bought a 2000 Ford Focus ZTS w/ the 2.0 Zetech double over head cam engine. The car had only 11,000 miles on it as it was owned by an elderly friend. I’m disappointed with the gas mileage. It averages around 25 mpg and I drive mostly highway (~20k per year). I previously owned a 1994 and 1998 Mercury Tracer both with the 2.0 engine but not double overhead cam and the mileage was much better. My driving habits nor my route have not changed and my tire pressure is fine. I have friends with newer models of the Focus who are averaging in the 30+ mpg range. What is wrong with my mileage? And also, any harm/benefit in going with oil that is 5W/20? My owners manual states 5W/30, but the newer Focus is recommending 5W/20.
Use the recommended oil.
Your mileage is lower than the EPA expects:
How do you drive it? If you go 65 MPH or moe on the highway, that’s your answer. If it’s more like 55 MPH, then it may be your style of driving. Or not. I don’t know you, so it’s hard to say.
Has your mileage always been this low? If not, you might need new plugs. When does Ford recommend changing spark plugs?
You can’t compare one vehicle to another for mpg comparison. Too many other factors involved.
If it’s an automatic, then your mileage isn’t off by much. It’s rated for 28 MPG highway.
In addition to what others have said, I will add this information. Ford retroactively changed all or virtually all of its passenger vehicles to 5w-20 for fuel mileage purposes. It is a very small gain. I doubt you will notice it. I continue to run 5w-30 since it is very hot where I live. You would be O.K. with either. If you change the oil twice a year or more in a cooler climate, I would go with the 20 in the winter.
25mpg isn’t particularly that bad given that your driving isn’t strictly highway. Consumer Reports got 17-19mpg in around-town driving with 3 different Focus models they tested, so if you assume 32 mpg on the highway then 25mpg combined sounds about right.
However I have a suggestion: you purchased a 6 year old car with only 11,000 miles on it. Is it possible this car saw tremendous amount of extremely short distance driving? Maybe 1-2 miles here and there every day? I might out of curiosity just pull a spark plug and see how they look. I have to wonder if they’re nice and clean with a good tip. Alos, have you investigated the possibility of a hanging brake caliper or emergency brake? If the engine is in good shape and the tires are inflated you should be able ot crest 32mpg on the highway even at 65mph.
Oh, and stick with 5W-30 engine oil in this car.