Technical While driving on cruise fuel usage doubled for 5 minutes

[MKoers]

This morning I was driving to work, doing the normal route.
As usual cruising on cruise control.
Speed around 80Km/h.

Suddenly the fuel usage doubled.
It went from 21km/liter to 9km/liter.

Nothing changed in driving. I did not hear strange noises, increased RPM or anything else.
I could see the needle of the tank level go down fast.

After about 5 tot 10 minutes the fuel usage was back to normal levels of 21km/liter.

What could have caused this?

I thought the engine had problem but it responed well.
And flat out it fast as usual.

 

[DlightSwitch]

Normally I would say it could have been a rough road, or a slight uphill incline where the car hard to work harder to keep at that same speed, but since it's a road you usually take, then it's probably just a glitch in the system. Unless it happens again I wouldn't worry about it.

 

[amcand]

If your car has a DPF it could have been on a regeneration cycle. This normally results in increased fuel usage for a while.