How long does new engine need to adjust for fuel economy

[Jorge13]

I was wondering who bought a new vechile. How long does it take for the engine Get the right fuel economy. Does it take time for computer and sensor adjust the engine for breakin period . Let me here your response my new vechile seem not getting good milage yet.

[trollbait]

Actually, most of the breaking in is in the tires. They have a higher rolling resistance when new. It will take a few thousand miles for them.

[JockoT]

I got two new tyres last summer and they ruined my mpg. I had only just got the numbers back up when I had to replace one of them, and now I notice the difference again.
Four, brand new, P285/45R22 AS BW tyres must decimate mpg, until such time as they have the edges rubbed off. I would imagine almost 5,000 miles (going by my experience).
Tyres are at their best, mpg wise, just before you have to replace them!

[trollbait]

The EPA doesn't allow more than 4000 miles worth of tire wear on tested cars.