Am I correct in assuming that adaptive cruise control will keep you car at a constant speed for the most part? If so, you may not want to use it much for the first 600 miles, while the engine is breaking in. The manual advises avoiding driving at constant speed during this period.

if you find that eco light annoying (I did), you can turn it off in the options when you move the gauge to the right

Thanks for the reminder CtSFox. In theory yes it should be constant but unlike regular cruise control it reacts the people merging in front so it's constantly adjusting. I'll keep your advice in mind and try to vary it as much as I can.

Gauge is wrong in my car...

Gauge says: 21.7mpg
Manual calc: 24mpg

Manual Calculation: 299 miles / 12.467g (filled up at gas station) = 23.98

I averaged 25-27mpg in my 2IS 250 so I'm pleased my MPG didn't drop too much. I would say that I drove 99% in Normal mode and 1% in Sport+ mode for break in reasons. The first 190ish miles I really babied the car and tried to stay below 3k RPM. Then 200 miles in I started opening it up to 5k and 6k RPMs.

60-70% freeway
30-40% city

I'm working on a manual calculation,so I can compare to my gauge, I'm only averaging 15.5 mpg but in 90% city driving

Any updates anyone?

My dealer's shop foreman reported this to corporate under Case Number TA140150158; please feel free to mention same to your dealer so we can get traction on this!

In addition to my own poor numbers of less than 14 mpg's, I see the following:

Jhooks (IS350) @ 11.6 mpg’s

KumaF (IS350) @ 15 mpg’s

corradoMR2 (IS250) @ 15 mpg’s

mnm27mnm (IS350) @ 15.5 mpg’s

Thanks.

I average 23 mpg in the city, its not heavy trafic though using eco mode about 80 percent of the time, i get about 25 mpg on highway using a mix of eco and sports + mode.

Is350

Thanks, tlr.

Yes, with the great mpg's others are getting, anything under 17/18 mpg's is not right.

Hope we can figure this out. :|

My 27.2 MPG only lasted for few days. After several stomps on the gas pedal now I'm hovering around 22MPG. Even driving in ECO mode doesn't seem to change this too much. I'm sure very cold weather we've been having isn't helping the MPG #s.

But my assumption is these auto calculated MPGs are not accurate. I'm going to check with each fill up manually but I'm still on my first tank since I'm keeping the car polished & garaged until I get my PPF this Thursday. ;)

I get around 15-17mpg, but I live in a very hilly area and commute is not very long but high traffic.

As an example, when we used to live further out (in the burbs), my wife's SUV used to get 20+ mpg. Once we moved close into town and very hilly, her car only gets 15mpg at best. Short trips and hills make a big difference but now we both drive much shorter distances so overall cost is lower (less gas and less miles).

I'm noticing that I may be getting .5-1mpg more with Shell gasoline over Chevron/Costco.

My 350 AWD is still averaging about 18-19 in all city driving. Romp on it a few times and I can easily and quickly lower that number. ;-)

Out on the highway, I get about 24. My last tank had a mix, and I averaged 21.

I've been calculating my mileage and comparing it against the displayed mileage. Yesterday I filled up and the display said 21.1 MPG. I calculated it and got...21.1. It's usually within .5 mpg. YMMV

This is normal for a 350. I get 14-16mpg and I do 100% city. This can also be partly blamed on the winter mix.

Here are my MPG for 100% City and 100% highway.

City 20 MPG, Hwy 29.7 MPG

Both are in ECO mode, driving it like a grandma with cruise control on.

I've been finding that the car's fuel economy calculations are remarkably accurate. The last two times I've filled up, they've been almost dead on (0.1-0.2 difference). This contrasts to every other car I've driven where they were consistently reporting 1-1.5L/100km better than I was actually getting.