I recently purchased a 2010 Outlander XLS. The manual says the break-in period is pretty short, only about 500km. Right now I sit at about 1000km so I'm assuming the break-in period is over.

On the first dealer tank (not sure what type of gas, whether regular or premium) I got around 375km - hard to tell to the exact km because I never filled it - and I filled the tank pretty much as soon as the light came on.

My next tank I put in regular gas and filled as soon as the light came on. I got 350km on that tank.

I just put the next step up in gas (91 octane I believe) and while I'm still not finished the tank I have 265km on just under half a tank..I figure I'll probably end with just shy of 400km...improving a little bit.

Should I expect fuel economy to improve any for the next little while or should I consider break-in finished and fuel economy is what it is going forward?

I'm going to experiment with the different octane levels and see what kind of mileage I get. All 3 tanks so far have been pretty much the same driving pattern - mostly city with a very small amount of highway. In my mind I think the vehicle is running smoother on the 91 octane..but that could just be in my mind

 

I have the 4 cylinder and my mileage increased after about 10,000 miles/16000 km.

 

I'd use the recommended octane spec'd by Mitsubishi.

The car computers are tuned to use a certain octane and will adjust spark timing a bit with knock sensors if you use something else. Octane only makes the fuel harder to ignite. This is done in engines that use a higher compression. The higher the compression, the sooner fuel will ignite. This results in pre-detonation, which in older engines (like my ranger) you'll hear them knocking. So if octane is increased, the fuel will ignite from the spark instead of from heat/compression.

 

Definately use premium man. The engine is desgined and tuned for 91 due to the higher compression. For the small amount extra its well worth it. And I'm still noticing better and better economy 7 months and 11,000 kms later. Its about hit its peak I think though.

 

Here in Australia you cant get anything less than 91 octane and soon 94 will be the lowest. Apparently its better for the environment. Its certainly helps performance and economy.
You should get around 700k to a tank without any problem.
Mine didn't seem to change from new. It had 6 kilometers on it when I got it and has now done 40000k.
09 2.4 4wd CVT duel feul

 

I'm assuming you mean 700km a tank highway...there is no way I could get that city driving.

My next tank I'm going to try the 94 octane. I think I'll be just shy of 400km on this tank city driving.

 

Don't waste your money. 94 is too much its not gonna make a difference. The car is only tuned to utilize so much octane. 91 is all you need trust me. I had a supercharged Cobalt which i tuned regularly and I've had this discussion a million times over.

 

700k + is about half hills and the rest highway. Venture into the city and it goes down to around 550k. Thats when the warning light comes on. Thats with my wife driving half the time.

 

Woot Minimum 91!!!

You guys are damn lucky.,..we still get the crap 87 and 89....91 is a luxury, 94 is priceless.

 

Considering that North America calculates the octane ratings differently than Europe, we pretty much get the same quality of gasoline as everyone else.

http://en.wikipedia.org/wiki/Octane_rating

Europe uses the RON rating where USA takes the average of RON and MON rating, essentially what Europe calls 95 octane, we call it 91 octane. So there is nothing to get depressed or excited about.