The ECU adjusts the timing to prevent knocking on 87 octane, under conditions of high load such as full throttle acceleration or high speed.

Adjusting means slowing the rate of advance and limiting the full advance. That costs power which costs economy.

 

Car and Driver did extensive testing of the octane myth on several cars a few years ago, including dyno measurements. No gain whatsoever in power or in fuel economy.

 

omg dont tell me those things are getting that low gas milage...i'm actually lookin at buying one while my tC is on overhaul next year. Wanted to get something cheap and good on gas..and stay in the Scion family

 

Read all the posts by the original poster...18" wheels, LA city driving, and he's an acceleration junky who likes to revmatch his downshifts...

 

^^^ Read MY posts then. I am getting the same...Yes I have 17's, but I baby it. The only time mine gets near and over 30 MPG is when we do strictly freeway driving. I'll post a link for you and you can tell me whay I'M doing wrong, ok? LOL.

 

Here you go Brambling...try to read through all 7 pages of it and maybe you can help us out here.

https://www.scionlife.com/forums/vie...914&highlight=

 

Have you tried going back to the stock intake? I seemed to fix itself once when you cleaned the AEM, maybe there is something wrong with it you haven't found out about.

 

I have been told that durring the breakin period that the MPG will be lower. Many owners have told me that I should start seeing the MPG go up. I have seen this happen at each fillup. Fjust an FYI...

 

Mine has been steady at around 35-36 since I got it new. I think maybe it just has to do with people getting used to the shift points and nothing to do with the engine breaking in.

The recommendations in the manual for break-in (such as it is) mostly read like it's for the benefit of the transmission.

 

The first time I filled up I barely got 23 MPG. The second time it was 27 MPG. I am hoping it goes up more than that.

 

I get the same 35-36 with my manual in daily driving. On a 275-mile trip to Cleveland, I got 37 going there on 2-lane roads, and 43 coming back on the Interstate. On the other hand, a day around and on a race track produced only 23 mpg. The mileage in an xB depends completely on the driver's foot.

The break-in is really for the engine, not the transmission. Varying the speed and not staying in one gear too long serves the purpose of constantly accelerating and decelarating the engine. It is not critical to the xB, but when breaking in a restored vintage motorcycle that costs the same as an xB, this same break-in method is the difference between several possibilites: a seized engine, or an oil-burning engine, or a good engine that burns no oil and whose oil stays clean for a long time.

 

Oh. Other than not going for long highway drives, the recommendations are not much different from what one would do for everyday driving.

I did do a highway drive during the break in, but I stopped once each way.

 

xB gearing is really short - the usual 15-25-40-45 shift points are too high if economy is your goal and it took me a few days to adjust my shift points. The car will happily cruise in 5th at 30-35.

I love passing Priuses. Given the driving habits of the average Prius (or any other hybrid) owner, I bet xB gets better gas mileage for considerably less moolah and headache.

 

And what's more, we don't have to suffer the indignity of driving streamlined cars.

 

It's the 17" wheels that kill mine. With the 17"ers I get only 28-29. With the steelies I get 32-33.

 

^^^ Yeah, but can you explain why mine was consistantly getting 30-35 (for months), then drop to 21-23(since Oct. of last year)? It has ALWAYS had the 17"s on it. All the dealer could tell me was gas. I gave up on trying to find an answer months ago, but it still bugs me. When we drove back to Louisiana fully loaded, it did get up to 38 at times, but it's back to it's old 22 MPG (and we're back in CA, too...hmmm CA gas THAT bad?).