Mileage and mods
 

Do intake and exhaust mods affect mileage? I get 24mpg highway in my bone stock '11. How about you?

Im going to say yes. I used to average 16-17mpg with a mix of city and highway stock. Im down to 13mpg with headers no cats and custom 3 inch dual with x pipe. Im guessing the more you mod them, the more richer they run.

Actually the exact opposite should be true. Adding headers and exhausts (and intakes to a very slight degree) should actually lean out your air/fuel ratios, which is a big part of the reason you make more power. Theoretically, you should gain a few mpgs by adding those mods. In reality though, your foot probably tends to be a bit heavier when you have more power on tap, so you might be driving a little more aggressively which absolutely negates any gains you would have gotten otherwise.

I have headers, no cats, magnaflow mufflers, and intake..pretty much all the mods possible..this weekend with 70% highway driving and 30% street I averaged 22mpg. On long trip I average 28, and in city mostly I average 16-18. sound like at 13 mpg you have your foot in it excessively. Because, when I would do hard pulls or runs for about 30 percent of the tank I still average 16 mpg.

Agree with this 100%.
Exhaust mods free up air flow. Assuming you drive the same before/after modding, your car is igniting the same 'x' amount of fuel with a greater amount of air (rudimentary explanation).
I maxed:woot: 28.5 mpg with headers, exhaust, joe z elbow intake, and the biggest contributor of all, issforged SKEWPS :D

weight saving, lighter wheels, lower car and body kit and of course, intake, exhaust and headers will save u some gas mileages but r u really about that when u own a v8 ;) no tool kit and spare tires, remove unnecessary in the car. Last but not least , most important is the driver weight lolz ;):p

I've been able to get over 30mpg driving out to Vegas using only half a tank. Being VERY conservative and setting the cruise control at 70. And I've got all I/H/E mods.
Attachment 307583

Of course on the other hand after a track day you don't get such good mileage (this was before mods)Attachment 307584

incredible highway mileage

Hmm, double edged sword. Now that I have headers, its constant driving like a nut just to hear it... Which lowers gas mileage. :)

Same goes for my 2nd cat / muffler delete, throttle blips are orgasmic now

Oh absolutely, my general average is about 18-22 only because I love the sound of putting it in manual and playing with the gears myself. Along with that occasional backfire and downshifting make my gas mileage something I really don't care about. I mean it's a V8 sports sedan, were you really thinking about gas mileage when you bought it? Gas was $4.35 a gallon for 91 oct when I bought my F five years ago and I didn't care then, I knew what I was in for.
I will say however that I still get better mileage off my F than my Chevy Colorado 4-banger work truck, I'm lucky if I get 15mpg out of the thing lol

Personally from just an HPS pipe, Joe Z exhaust and the magical ISS Forged scoops I've been getting 24 to 25 MPG average with mostly highway cruising at 65MPH and the occasional "spirited" sprints here and there. Under more interesting circumstances I'd see an average of 17 MPGs. It would be nice to see higher MPGs once I get my headers but I didn't buy the F for economic gas savings. :-P

I've seen anywhere from 5.2 to 29.0. All depends on how you drive. Mods don't make much difference at all since high mileage will be achieved in closed loop when the wideband O2 is targeting very specific A/F ratios. Yes, the primary O2 is a wideband, and yes, Lexus targets A/F ratios with this device.

Tire selection and air pressure have a bigger impact on highway mileage than headers, intake, and exhaust.

I agree, ISF shouldnt have been bought or modded for fuel mileage, but they do make a Lexus HS250 Hybrid for fuel mileage :)