I average 23-24mpg in my IS350 city/hwy mixed. Will get 30mpg on highway trip. A 250 should be getting 4mpg better on average than the 350.. so i would say something is wrong

 

I don't know how much of a difference AWD vs RWD makes but my IS250 RWD gets about 25mpg in the city too. So i'd say time to take the car in or have service done or something because i cant imagine the difference between 8 mpg RWD vs AWD.

 

The car is basically pretty new... 5,000km on the odometer.

 

I see.. I guess I'll just have to get used to it. xD Can't just think how my dad's cx7 can get better mileage than my sedan.

 

I complained about my gas mileage too when I first bought my car. I did a lot of learning, observing, and other crap too see why my car got such bad gas mileage. I have an '07 IS350 RWD. First weeks I had the car, I averaged 11 MPG combined. That was when I was showing off in high school with the IS and taking off at every light. Sometimes, it got into the single digits for the fuel economy. I then realized I was refilling too often and I started getting tired of the care so I began driving more conservatively. However, I was still getting 16 MPG combined. I went to the dealer and complained why I wasn't getting 21-28 MPG. They gave me the obvious, "with city traffic here, it can easily go down to 16". They checked out my car and said nothing was wrong with it. I did all the maintenance, tire pressure, oil change, air filters, and spark plugs. I got another 1-2 MPG better. Now, I average 19-20 MPG and I'm satisfied. I realized to get the 21-28, you need to be very gentle while driving. My commute is 18 miles highway and 17 miles city. I one time got 34 MPG driving only on the highway and 25 MPG city but that was with really slow acceleration and letting it roll most of the way.

There's lots of reasons why you only get 17 MPG. It can be where you live. In Chicago we I live, there's stop signs every single block and red lights every quarter to half mile. In city alone, I get about 14 MPG. Also, gas is wasted if you idle a lot whether you're in your garage or whatever for times. My friend with an IS250 AWD gets 20 MPG as well and a Lexus mechanic I talked to gets 21 MPG in his 2011 IS350 AWD so everyone I know is in the same range.

 

Is it a Lexus technician you went to? All the ISX50's make a ticking sound and it's normal. Plus, last time I talked about valve adjustments, the ISX50's actually come with hydraulic valves that NEVER need to be adjusted. At almost 100,000 miles, maybe consider changing your gasket like they said since it could be letting oil through.

 

It wasn't a Lexus technician I went to. I should be changing the gasket though, just not sure about the valve adjustments.

 

For my 350, I get average 19 in city. If I try 5secs at every green light kick-off return then probably 16 ; Get 28-30 on freeway when cruising.

 

IS350 city driving 18-19.
Miss my civic mpg.. was getting 27 in the city lol.

 

GET A TUNE UP! New spark plugs, reset your ECU, new oil, new everything. Do that and your **** will fix itself.

 

I average 17mpg driving in the city in a IS250. It's San Francisco though, either red light or stop signs every 500 ft with addition of hills.

 

I really don't keep track of miles in city nor on highways. I assume I do pretty good because I only drive 12 miles round trip every day Mon. - Frid. from work to my house. The good thing is that eventhough, I drive on the street, when I go to work at 1:00pm and return home at 9:30pm, there isn't any traffic and not many stop signs and most of the traffic lights are green. On weekends I do most highway miles. I only have a 95lb. passenger and always keep my tires inflated as recomended.

I did notice one time I was waiting for a date ouside her place that my average miles on the display screen did go down two miles because I had the car running for about five minutes. Since then, I turn my car off even if I have to wait for somebody for a minute. I figure that the more red lights we stop at the more gas we use. Driving on main boulevards is best when not so congested because lights are programmed to stay green longer than other intersections. Not unless, all intersection in the area get congested. Then all lights will be programmed about equally. So driving on side street is not awlays a good idea because you may end up making more stops and waiting longer for red lights to change. I guess we just have to use common sense regarding which streets/boulevards to use on our daily commute.

Good luck