Why am I suddenly getting poor economy from my car?

I recently purchased a 2004 Mondeo 2.0 LX auto, 175000 miles, and am only getting 22-24mpg around town when I was expecting 30mpg. The owner's manual suggests a range of 395 miles; I'm getting barely 300 miles. I have changed the oil and all the filters, plus spark plugs. Tyres have good tread, wearing evenly, and are at correct pressures. I am using premium petrol, only. The engine runs very well, with no hesitation under load. No leaks, or petrol smells noted. What do you suggest I try next?

Asked on 11 April 2023 by Paul Townley

Answered by David Ross
Fuel consumption has a huge number of variables that can affect the outcome, and particularly with an older car, even if it is kept in immaculate condition the years of service can take their toll on how a vehicle performs.

Looking at the official fuel consumption figures for your car, the urban figure is 22.4mpg - which is exactly what you appear to be getting - while the combined figure is 31.0mpg, which incorporates some higher speed driving. We suggest you reset the trip meter and take the car on a steady 30 minute drive on a dual carriageway or motorway. If it returns a figure of over 30mpg for this journey it would suggest there is no problem.

It's worth remembering that the Mondeo is quite a large car, a 20-year-old design and has a naturally-aspirated engine with a torque converter gearbox, so even if it were brand new it would still be a relatively thirsty machine.
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