JBrady

I average slightly over 20mpg combined daily driving and usually refuel with about 18 gallons so my normal would be 360+miles per "tank". That said with a 21.9 gallon tank my normal theoretical tank "range" is 438 miles.

Below is a picture after going 503 miles. Computer said 36 miles remaining, average speed 76mph, 26.9 miles per gallon.

26.9 mpg gives a theoretical 589 miles. Not sure how accurate the computer is but the miles driven is of course accurate. Once the low fuel light comes on the range readout states "Range Approx 50 miles" which is not accurate if you continue to drive in the same manner as I drove well over 20 miles with the computer down to "Range Approx 36 miles".

The above effort was not really trying just normal cruising with stops including quick accelerations back to crusing speeds and passing vehicles as needed. I drove from Houston to New York with a bit more effort but not max effort and got 28.9 mpg for the trip giving a theoretical 632 mile range. I have also topped 30mph for shorter distances so 660 mile range is theoretically possible with 700+ in ideal conditions. Pretty impressive.

For those wondering how? CAREFUL throttle modulation. A STEADY throttle foot along with carefully timed use of power. SLOWLY accelerate when going downhill and allow the car to SLOWLY decelerate going uphill. Of course I am talking about minor up and down hill situations on interstate driving. Your throttle foot should get VERY smooth with NO input unless NEEDED. Select the averge MPH readout and watch what it does as you drive. Over time you should be able to improve your "style" and get more efficiency.

I ALWAYS use premium fuel which is 93 octane in Texas. Use of 87 octane will function (obviously) but the computer will adapt my pulling timing and reducing peak torque and power by -25hp/tq or more.

lexuskim

What am I doing wrong!? I use premium fuel but only get 240 mpg at most city driving and 275ish highway and city? Help!!!

RA40

iTrader: (6)

One aspect of having the GPS is the Eco challenge. This feature charts acceleration, braking and combines a preset factor of speed to determine what is going to yield good MPG. A 99 score is usually falling in the 60-69MPH range. The scoring drops if dropping below 60 and above 70. It drops 1-2 point for each MPH. The higher the speed, the quicker the scoring drops.

I don't pay much attention to this though it does give an idea how I apply the gas. As JBrady mentioned, being smooth does wonders.

lexuskim

What am I doing wrong?! I use premium gas and only get 235ish MPG. in the city and 275ish highway. HELP!!!

PureDrifter

iTrader: (10)

98-00 get better mileage than earlier cars.

curepunx

iTrader: (3)

I know this thread was directed towards the 2.1LS but my 1LS has odd mileage at times but i suppose it's due to the weird driving patterns.

*Based on approx. 18-19 gallon fill-up*
City/Highway mixed driving: ~350 miles/tank (city/highway commuting)
Mostly highway driving: ~450 miles/tank
Mostly city driving: ~300 miles/tank

I wish it would get a few MORE MPG but it is what it is.
Love the LS though

LS430Lexus

If I drive "smoothly" and take it easy on the highway, I can get close to 400 miles on a tank. Does using the cruise control have a positive or negative effect on mpg? I have heard it both ways.

zukikat

You sure you don't have a bad thermostat or something else wrong?
I have a 94 and have only refueled it twice in the 2 weeks I've owned it and cruising at quite a bit over legal speeds, and idling for 10-30 minutes at a time while troubleshooting, and even having an eventual catastrophic ECU failure earlier this week that was intermittent when I bought the car and running the car so rich most of the time that the exhaust actually made my eyes water as I walked around the back of the car with the engine running and I still got well into the mid 300's per tank on a mix of city and interstate driving with an average of 17mpg and a 19.5 gallon fill-up with Chevron Premium 93 Octane gas.
I'm expecting consderably better economy in the low 20's at least from this next tank as I've swapped out the ECU and the car's behaving a lot better now, isn't running crazy rich anymore, and isn't threatening to leave me stranded and then reporting that everything's fine when I ran diagnostics.


As for cruise control and fuel octane and such...

Cruise control can be far more smooth and stable and consistent than most people can be with their right foot so as a result it will typically yield superior fuel economy, although in "hill country" all bets are off.
Plus if you set your cruise at 75 versus 70mph you probably won't notice too much of a drop in range but if you set it on 80mph it should be a significant reduction in range, although that will vary by model year as the vehicle's gearing ratios are changed by Lexus....

When it comes to using sub-par fuel, a buddy of mine swaps performance engines into lightweight vehicles as a hobby and went hunting for a 1UZ last year to either twin-turbo and/or "spray" and he found that he could always tell the 1UZ engines that had been run below specified octane most of their lives because they always had premature engine failures and/or at least signs of cracked pistons and other nastiness, although most of them had well over 200k miles on 'em by the time they did fail but not always, whereas he saw many 1st gen LS400's with far more miles on them in far better internal engine condition which is more typical of a well maintained and properly operated 1UZ engine...
If you drive like a lazy old man trying to hyper-mile it on flat terrain and never go over the speed limit I'm sure you can get away with 87 Octane, but if you drive "spirited" or even agressively, stick with 91 Octane minimum, after all, it's not even $5 per LS fuel tank worth of difference in cost from the cheapest gas to the best gas at most fuel stations and what's that going to get you, another cup of coffee or a fast-food burger or a foot-long subway sandwich maybe??? It's NOT worth it to skimp on fuel, it just isn't.
Look at it this way... If you could buy more fuel with the savings, how much further would that get you? Maybe 20 miles, 30 miles, 40 miles, if that far???
Is it really worth saving those few bucks per tank to reduce the overall longevity of your engine? No it's not. Will it die the day after you run "regular" gas, no it probably won't. Will it die from running 87 octane while you're still the owner? Depends on how agressively you drive and how long you try to own it.

Also, gearing makes a HUGE difference in fuel economy but can also impact performance. I forget which year got a 5-speed transmission but that year probably also got a different "rear end" (differential) ratio specifically to improve fuel economy.

The older years like mine are rated low 20's on the highway and probably can get into the upper 20's on the interstate at the posted speed or lower.

I've gotten as much as 27mpg out of my old 1998 Twin-Turbo Supra with the A/C ON the whole time and quite a few performance upgrades done to it (450hp at the wheels on 93 octane "pump gas") and as little as 10 MPG on the highway from that same car with those same upgrades on it.

The lower the grade of fuel used below the factory recommended octane level, the lower the fuel economy I've gotten when it comes to japanese cars.

The faster I drive above 75mph the far more rapidly my fuel economy drops.

You have to figure out what the fuel economy sweet spot is on your tach for your car's gearing if you want to maximize your car's range per tank.
You also have to be willing to cut back on speed and agressiveness with the right foot if you're a "spirited" driver who wants better economy.

I've taken a 4cyl 1996 Camry DX base-model and gotten as much as 32mpg and as little as 21mpg on the highway from that same car and the differences ranged between a/c use (better with it ON!!!) and fuel octane (it liked 89 mid-grade best) and a cruising speed of about 65mph (cruise control used) for well over 500 miles per 17 gallon fill-up versus 350-ish if I was being overly agressive at considerably higher than posted freeway speeds and driving without the cruise control on the same exact 50 mile interstate work commute in that car...

With my driving style I'm expecting 19-21mpg (hwy) out of my 94 LS which is about what I used to average in my Turbo and Twin-Turbo Supras and my stock '01 and '02 IS300's in past years so I'm used to that mpg range and I'm okay with it personally but I'm sure I could personally hit 25mpg or better in this older LS if I really tried...

We'll see how it goes after a few tanks once I get a properly working ECU.

sdls

I've come that far doing pure highway driving with my '96.
However, for cold-start 2 mile trips, it's absolute MURDER on fuel. Feels like 5-7MPG.

JBrady

The 90-97 models had the 4 speed, 3.62 differential and .705 overdrive giving a net 2.55 final ratio.

The 98-00 models had the 5 speed, 3.26 differential and .753 overdrive giving a net 2.46 final ratio.

genetic

iTrader: (1)

Wish I had a 98-00 LS400!

damn

zukikat

Those can be found for reasonable prices these days but I chose my 94 on a whim, mostly based on price and location and the salesman's patience and flexibility with me and other than the damn ECU failure it seems that it was a good purchase with more than reasonable fuel economy for such a big heavy car.
There was a 98 in my area for less than $9k with like 132k miles on it but I didn't like the ghetto fabulous wheels and aftermarket alarm and "stereo" (amps/subs/tv's) that were in it and the dash cluster that was lit up like a christmas tree with warning lights and the check engine light was on and the private seller knew nothing about the car's history and didn't seem concerned about all the warning lights at all so even with a clean carfax and the fact that it seemed to start right up and run fine I passed on it anyway. I'm sure somebody got a deal on it but it was more complicated and problematic than I was looking for. There were others with less issues for slightly higher prices as they've now passed the decade old mark but so far I'm happy with my pretty clean 94 LS.

smokincigs

This is my 2nd 1998 I ran premium when I first bought both cars. I cant tell a difference in the way they run or sound. Very smooth with no knock.

fatcat2

wish i was seeing those numbers when i had my g35, on a full tank i could squeeze roughly 400 miles out of it(20gal tank). I'm looking forward to getting a ls400:-D

RA40

iTrader: (6)

Ours does well with Shell premium that I seldom put anything else in. Theoretically given a flat road and using our best MPG numbers taken from the GPS, ours could get 500 miles at 20 gallons. I tanked up with 480 miles in Jan and put 19.X gallons in on that run.

The GPS gives me an approximate difference from the OD/trip meters on the car of about 1% overall. If I tank up the car meter reads say 400, the GPS will show me ~396 miles. Given the tire diameter, this comes reasonably close. If the GPS has an accuracy of about 15' or so, I would have to calculate the error rate per mile. I'm to lazy to be that OCD about this.