Slust, I have almost 6k miles in a 350 fsport. Last 6 fill ups I'm averaging right at 23mpg. I use the old fashion miles/fuel formula.

 

i use Normal mode and got 17mpg for daily drive, full tank fuel show only 267miles and now im thinking about drive from san jose to La, i wonder 1 full tank can handle it or not?

 

I've had my 14 IS350 F Sport RWD for a little over 1 month, it's got almost 900 miles on it, with about 70%city/30%hwy driving in primarily Normal Mode, my MPG indicator is at 18.7. I'd like to see it above 20mpg, but unless I did more hwy driving I don't see that happening.

 

Thanks to all those contributing to the thread!

I see a few wondering why their gas mileage isn't as good as some others. I keep saying this, but I will say it more bluntly... location, location, location. Have you noticed most of the people with the gas mileage problem are New Yorkers, Californians and a some Canadians? I can't speak for those in Canada but I seen first hand how horrible New York and LA traffic is. Granted 11mph seems absurdly low but my IS250 got 14-18mpg in DC. If I had my 350 there I'm sure it would be lower than 14mpg.


Also the type of gas you fuel up with definitely affects your gas mileage. I got a free tank of gas, supposedly it was premium but I have no clue what it was or where it came from but I got 2-3mpg less on that tank - was dipping into 19s but I think I brought it back up to 21. Free gas is free gas but wow I couldn't wait to get a fresh tank of gas in, it even ran slower. Put premium Chevron in this previous fill up, now the gauge reads 22.7mpg so it's most likely 23.3mpg since my gauge is typically off by 0.6.

Sport Mode 99.9% with probably 50/50 or 60/40 freeway and city mix. I don't baby the car anymore.

 

It's way too early to tell but with a whopping 125 miles on the odometer my IS350 is getting 23 mpg and climbing in perhaps 65% highway -35% city on my work commute of 25 miles. I'm still on my first tank and the car sat in the dealer lot idling for quite a long time while they showed the tech. To compare, by 06 Acura TL 6MT averaged 25mpg on a similar commute and it was very efficient. Granted I am babying the iS and have not come close to WOT I am happy that I can get that kind of mpg if I want to.

My secret? As I've mentioned in previous posts, if you are trying to accelerate hard in eco mode you are wasting gas. If you are driving easy in sport you are wasting gas. I spend most of my drive time in eco and when I need some more acceleration merging into traffic, etc. I'll put it in normal. Sport is only when I really don't care about gas mileage. LOL

 

I've now driven most of a tank primarily in Sport mode with my IS350. My numbers are as follows:
ECO: ~22mpg
Normal: 22-23mpg
Sport: 19mpg
As someone point out, you do take a BIG hit when idling. As I constantly monitor the mpg display, I've noticed that you easily lose .2-.3 mpg just sitting in a drive thru. Other than drive thru's, I don't idle too much.

The biggest problem with sport mode is that you really cannot coast, which is something I like to do, such as coasting down the off ramp from the freeway, or coasting as I approach a red light. You can always manually switch to normal mode, but it would be best if they could offer a hybrid normal/sport mode which allowed the car to coast.

 

Well I am getting the same gas mileage as you in Sport mode, so I dunno. Sounds like you only drive in Eco mode for most of the tank, you should test out the other modes and see what you get.

As it stands right now, I don't see any point in driving in eco mode - and that's babying it in eco mode. Right now my best tank was my first tank in which I spent 100% of the time in Normal mode and completely babied it (drove below the speed limit, didn't pass anyone, etc.) and I got 24.0mpg. This last tank in 100% Sport mode turned out to be 23.4mpg. So I only lose 0.6mpg by driving in Sport mode with plenty of 80-100mpg passing. Now if I could save 5mpg++ in eco mode, I would be more tempted to drive in Eco mode.

I've tried full tanks in Normal, Eco and Sport mode. The numbers are what they are. I even included my driving habit in the OP.


Thanks for the addition. So your Normal and Eco mode numbers match mine, almost exactly. Though your Sport mode does not, interesting. Did your driving habit change?

I will say that I hardly idle and I've noticed the same as you where idling seems to chew thru gas. I don't do drive thrus. Also the street lights are much kinder here than they were in VA/DC. In VA/DC some of lights took 6min (timed it) to change where as here they are about a minute.

You can coast in Sport mode if you go into Manual as the car won't downshift unless you bottom out your speed. I actually like the way Sport mode behaves because I don't like slamming my brakes or riding my brakes either. So while others ride their brakes down the off ramps, I just let off the gas and gently coast behind them. I also find it easier keeping up in thick traffic (not the DC type where you stop for a minute, drive for 5s, stop for a min, etc. type of traffic ...ya not that) in Sport mode . I just coast behind people and then gently press the gas when they do their accordion (speed up, slam on their brakes) to keep up. I try to avoid using my brakes as much as possible so Sport mode is great for me.

 

I drive exactly how you described...S+ mode gives me 20 mpg, but im in a colder region so maybe that's why you get a few more miles to the gallon than me...

 

What's sport vs sport+ mode? I can see the "sport" mode option next to the normal and eco mode options thingy.

 

Difference in the 2 is suspension. High rev driving is the same in both

 

Interesting thread, I own a LS460 and I love the way the IS350's look, it being a smaller car I figured the fuel economy would be better, but it isn't. Did a little research on them last night, they get very favorable reviews against the competition.

I average 26.5 miles per gallon in my 460, but that's just because of the way I drive. Most of my driving is highway, I almost never find myself in traffic (thank god) and I've really learned how to keep the thing averaging the best fuel economy possible...it's a heavy car and once it gets going it just rolls and rolls. Going down hills you never have to touch the gas pedal and you'd be surprised just how little you need to put your foot into the gas pedal to keep the V8 moving...and an 8 speed transmission really helps (averages 30 mpg on the highway, idle is always low in most driving conditions).

The type of driving I do is not exactly "fun". A month after I bought the car my commute went from 300 miles a week to 600, so I decided I was either going to sell the car or make some driving adjustments. To my surprise I'm able to do very well, I wonder if someone like me could average 28 in a IS350? By the sounds of it I doubt it, and the temptation do drive the thing hard would probably be too much for me...the IS350 is a different animal than what I'm used to.