Kia Service Issue

[Hysteresis]

My wife has a Kia Picanto, had from new only done 10,000 miles in three years. Had first service at 3,000 miles and second service at 10,000 miles.
I check the petrol consumption regularly by Tank fill to Tank Fill and check the mileage, as such I can get an accurate measure of mileage.
Throughout 2022 I have consistently recorded 47/48 MPG.(The on board computer only indicates 42 and the Kia dealer can't recalibrate the indicated MPG)
Immediately after the Second service, the Mileage dropped 20% to only 40mpg. I have contacted Kia and they are to relook at the car in January.
Has anyone any advice as to why this dramatic increase in consumption could occur Immediately after the service.
The car is running as before with no apparent signs of timing issues. Any advice would be appreciated as I anticipate a disagreement with the Kia Service Centre is ahead. It must be something they did at the service as the change in consumption was immediately apparent after the service.

 

[carmanmemoranda]

Actually mpg via tank full to full or indicated on dashboard ?

 

[fourtytwo]

Sounds like it might be in limp home mode, sure the engine check light isnt on ?

 

[Hysteresis]

Actual Tank Full to Tank Full MPG was 47/48 MPG before second service, Immediately After second service Actual Tank Full to Tank Full MPG was 40 MPG.
(The on board computer MPG is not accurate)

 

[Hysteresis]

Sounds like it might be in limp home mode, sure the engine check light isnt on ?

No indication lights on at all, car running OK but high consumption Post service

 

[RandomGrinch]

Was the tank fill just a top-up, and you've driven only a few miles?
Or, has there been a significant distance travelled since the service?

 

[Old Salt]

Handbrake adjusted too tight, rubbing and creating friction increases fuel consumption. Take it for a run and then feel the hubs to see if they are hot.

 

[Hysteresis]

Was the tank fill just a top-up, and you've driven only a few miles?
Or, has there been a significant distance travelled since the service?

Twice refilled tank from a very low near empty , recorded mileage, ran car for over 200 miles, did his twice after the service and on both occasions returned 40mpg. Before the service, the same procedure returned 47-48 mpg.
The type of driving is identical, low acceleration gentle braking and local distances on dual carriageways and major roads. The type of driving before and after the service are similar but the recorded consumption is substantially different.

 

[Hysteresis]

Handbrake adjusted too tight, rubbing and creating friction increases fuel consumption. Take it for a run and then feel the hubs to see if they are hot.

Thanks, I will certainly investigate that suggestion.

 

[just pumps]

E5 petrol used?

 

[Hysteresis]

E5 petrol used?

E10 both before and after the Service,

 

[Burnerman]

Have you checked the air filter condition? Not that that should make an immediate difference!
John

 

[Hysteresis]

Have you checked the air filter condition? Not that that should make an immediate difference!
John

Not checked the air filter for two reasons.
1.the air filter should have been changed at the service probably unnecessarily as the car has only done 10,00 miles.
2.the car is running well and no indication of an air filter problem such as problems with performance.
The only indication of a problem is a sudden increase in fuel consumption,

 

[Burnerman]

Any sign of soot deposits in the exhaust tail pipe? A bit corny these days, I know!
I think I’d let things settle down during this extreme cold weather and take the car for a good run to get the catalytic converter very hot, and see if things improve.
John

 

[Harry Bloomfield]

Twice refilled tank from a very low near empty , recorded mileage, ran car for over 200 miles, did his twice after the service and on both occasions returned 40mpg. Before the service, the same procedure returned 47-48 mpg.
The type of driving is identical, low acceleration gentle braking and local distances on dual carriageways and major roads. The type of driving before and after the service are similar but the recorded consumption is substantially different.

The weather has been significantly colder, so might that account for worse mpg?