I take the number of miles driven and divide it by the exact amount of gas I fill it up with. IE: 370 miles / 16.2 gallons.

Different pumps will probably have different shut off sensitivity but this will work for a good approximation.

 

you need to find out the REAL mileage you drove since your last fill-up and divide the # of gal of gas when you fill it up......

 

Be mindful of your right foot. Even if you are not hammering it try to maintain a steady cruise. I've been with some drivers that, even at a steady cruise, they are on and off the gas constantly, and they don't even know it. It drives me nuts! Talk about bad gas mileage! Also, if you drive spirited even just a little bit, your mileage will decrease significantly. I've been able to average 28 and then open her up just once to 100 or so and back down to cruise and did a re-check and was now averaging 19! It doesn't take much. My actual mileage is 21, mostly city.

 

Wow some of these MPGs are alittle low.

I'll harp on this again. My car recently broke 18k miles. My commute is about 90 miles round trip.

I use Chevron gas (Only stuff I'll fill up on!) and my latest tank averages have been 382 to 386. I drive roughly 80mph and average anywhere from 25.6 to 26 mpg. If I slow down and drive 70 I get closer to 28. I'm very happy with my gas mileage, as more mileage is put on the car it seems the better gas mileage I am getting. I use DINO oil too.

And if I make a quick sprint from 80 to 100 my AVG for gas goes down a couple tenths then creeps back up as I drive. Luckily I do majority I-State driving.

 

i really doubt you are filling up 17 gallons each gas up. 100% city driving I get 320ish for 14.5-14.9 gallons

 

Man... And all that is why Im glad I got a 250. Im looking at around 25mpg with and AC on a lot and a heavy foot!

 

With my 350, I get 25-26 with a light foot and the AC on...and I bet I can still beat you with your heavy foot.

just playin.

but seriously, I do about 60 miles per day, 20 of which are back roads. I fill up with 93 octane and I get 375-385 miles till empty, and my odometer confirms that its very accurate.

I'm not complaining! There is a whole thread on this...and i'll say it again...If i can afford a Lexus, I can afford the gas!

 

I actually dont mind 4buck a gallon gas, reason being commuting traffic seems to have lightened up. My assumption is people that it hurts are either finding alternate means (car pool, bus...ect.) or stoped their mindless wandering on the roads for no reason. Since there is less stop and go and more constant speeds I am getting better MPG. But then again i didnt buy this car for its fuel economy.

 

I have 7000 miles and I have never broken more then 17 mpg on my IS350 yet

 

just be glad you didn't get a rx-8.

14 mpg average

 

I'm an aggressive driver on 80% highway/ 20% city roads. A normally avg about 24.5mpg. Just for kicks, I drove 70mph, with the traffic instead of passing it at 80mph, and consistently got 32mpg avg. It's a 68 mile round trip each day.

The difference between my aggressive driving(24mpg) and stay with the traffic driving(32mpg) is a HUGE difference.

I've started letting up on the right pedal, but not by much. I love the horsepower to much. My previous car only had 124hp, so I have fun with this car and it shows with lower fuel economy.

And yes, I have a 350.... at least that's what I paid for.

 

Today, I just squeezed 60$ /17.797 gallons of 93 octane gas in my car!! Lexus says the tank holds 17.2 gallons, {plus the plumbing I guess}. I have been pulling a "Kramer" lately just to see how far past the miles to empty I could go. Yes, I know that is not a good idea, but I wanted to know my limits. A few times, I went 10-15 miles past 0 miles to empty, and when I filled up, I could only get around 15.5 gallons in, so I figured Lexus gives us a nice, safe cushion when the fuel light comes on. Today, I drove 20 miles past "0", and then filled up to the brim with the 17.797 gallons. My testing is now complete.

I drive 100% city, about 50 miles a day, with the A/C blasting and my right foot mashing . Avg MPG is 16-17. Even with my huge fill up today, the miles to empty only read 269, which is normal for me. I just can't help myself.

 

There are some shady stations out there that have pumps calibrated a bit off to charge for gasoline that isn't really purchased. Call your county/state inspector or whoever handles that, and they will take it very seriously.

With rising gas prices there is a greater incentive for these individual dealers to make a few extra bucks. There's always those out to cheat people. Especially now that if they can get an extra 3 bucks for every 10-15 gallons of gas, and they are selling 2million gallons a year (larger stations) that's quite a tidy profit!!!! Most dealers are only making an average of 7-11 cents a gallon.


Anyway a good suggestion to those looking for more MPG is to try driving with the current MPG bar. You'll quickly see what different driving does to your mpg.

 

I call BS on a lot of claims of 25mpg+ with the 350, UNLESS you achieve this after 5k+ plus. I have 1,700 miles or so on my IS and average 19mpg. Trust me, I drive SLOW (I'm on 20s). I never drive faster than 60 (55mph speed limit on my highways) and keep the RPMs very low in the city driving around 35mph.

A friend of mine has a 250 RWD and also achieves nowhere near 28-32mpg that's advertised.

 

my 350 is still pretty new, so my mpg might change later on, about 1100mi on it total and my mpg seems to be about 22-24 depending on how much traffic i get stuck in. i drive about 65/35 city/highway, i usually go no more than 5 over the speed limit(65mph highway). the onboard mpg calculator has been pretty accurate so far but i've only filled up 3 times so far with my current tank about half full. im pretty light-footed and i let my car cruise on its own to stop lights but i do like to gas it from time to time. no sense buying a car like this if you aren't going to utilize its power from time to time right? else i would've gotten a 250. and if i was worried about gas i would have bought something more fuel efficient, maybe a GS450h?
On the most fuel efficient speed for a car i remember watching a report once on tv that said most cars get their best fuel efficiency cruising around 50mph. for me out here, when i cruise around 50mph the mpg meter seems to hover around 30.