Ls400 With Improved Gas Mileage

[akewlguy]

I know the last thing most owners worry about is gas for their $50,000 LEXUS, but this may help us LS400 owners. :)

Over the past few weeks I have continued to test my mileage as I drive from state to state and this is what I discovered.

My typicall highway miles are at 75-80 mph. I keep the car between 2200 and 2800 rpm. I try to keep these factors consistent, but I am not a big fan of cruise control so its not constant.

PREVIOUSLY POSTED: Windows down increases drag and thus decreases mpg. This is true. MPG went from 19/20 to 21

PREVIOUSLY POSTED: Cycling AC on and off helps mileage. This is true. Mileage went from 19/20 to 21.

Combined I am at about 22mpg on a 80% highway and %20 city breakdown.

Sometimes I also roll down the rear windows slightly and dont find much difference.

Maybe this does not effect us that much, but a month ago I was at 380 and the orange light came on. So from then I have been open minded at ways to get this to at least 400. Anyone know how many miles the orange light covers?

[PK_Lex]

22mpg is a pritty good mpg. I usually top off at 21 on hwy and stay near 19 with mixed city/hwy driving. I've changed the plugs, wires, air filter, cleaned fuel injectors and checked tire pressure to be at 29.

From what I've read on other posts some people get close to 30 mpg...don't know what they're doing to get that.

To answer your question, the most I've gone with an orange light is 30 miles. I wonder whats the max it can go.

[wwest]

You can avoid cycling the A/C on and off manually by simply putting the temperature control in max cooling and the system in recirculate. Then use the blower speed to adjust/set your comfort level.

NEVER use reciculate if the OAT is below 50F.

In automatic mode the Lexus climate control uses a reheat/remix mode wherein all of the system airflow is first cooled via passing through the A/C evaporator and then a selected portion is reheated via the heater and then remixed with the cooled airflow.

Using max cool bypasses the remix/reheat cycle and results in greatly reduced operational cycling of the A/C compressor.

[sha4000]

22mpg is a pritty good mpg.  I usually top off at 21 on hwy and stay near 19 with mixed city/hwy driving.  I've changed the plugs, wires, air filter, cleaned fuel injectors and checked tire pressure to be at 29.

From what I've read on other posts some people get close to 30 mpg...don't know what they're doing to get that.

To answer your question, the most I've gone with an orange light is 30 miles.  I wonder whats the max it can go.

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i get close to 30mpg but thats only on trips of3 hours or more when i have an aerage speed of 80+ all other times i get the same as you guys

[akewlguy]

You drive 80 for 3 hours and get 30mpg? WOW

I would think one would have to drive 55 to get that..

[flanker271]

On my trips from Tucson, Arizona to San Diego, here is my report:

For winter driving with all windows closed, a/c off, stereo on, I get 26 mpg dead on at 76-77 mph with cruise control.

For summer driving with a/c on and stereo on, I get 23.4 mpg at 76-77 mph using cruise control during the entire trip. I can make the trip on one tank, but thats pushing it. I always set my tire pressure at 35psi.

I can't imagine how a V8 engine and a car this size achieves 30mpg. How is it physically possible?

By the way, at 75mph my engine is at 2500rpm dead on.

[SRK]

On my first big road trip with the LS I got 29 mpg (imperial gallon, so about 25 to a US gallon). That was at 75 mph, through the mountains, four people on board, and AC all the way, for 2200 miles. Unbelievable. I don't know how Toyota figured out the fuel control on these engines, but they did one helluva job. My GS does even better.

Try that with a Ford Exploder.

[baul79racer]

Hi I have a '91 LS 400

One day I started from my house in Bellevue,WA with the orange light already on.

From there, I travel to Tacoma,WA about roughly 31 miles and still going I had about 2-3 gallons left in the tank. If someone really want to find out go ahead and bring some fuel with you in the car and drive it until it exactly runs out but keep track of the miles when the light comes on. Sometimes the lights comes on and then goes away and finally then stays on firm.

My tire pressure 32 psi. And everything is checks out fine.

Paul

[sha4000]

Hi I have a '91 LS 400

One day I started from my house in Bellevue,WA with the orange light already on.

From there, I travel to Tacoma,WA about roughly 31 miles and still going I had about 2-3 gallons left in the tank. If someone really want to find out go ahead and bring some fuel with you in the car and drive it until it exactly runs out but keep track of the miles when the light comes on. Sometimes the lights comes on and then goes away and finally then stays on firm.

My tire pressure 32 psi. And everything is checks out fine.

Paul

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my low fuel light usually comes on when my iformation center rads 50-60 miles left on the tank of gas. i drove another 40 miles one time from nyc to north brunswick,nj. i dont know how these cars get such good gas mileage but it seems the faster i go on the highway the more gas mileage i get. i drove from ga. to ny and had to fill up once, i had gone like 470 miles b4 i stopped for gas and i still had just under a quarter tank left

[SRK]

Running a fuel injected engine out of fuel is never a good idea - even running around with a very low fuel level is nearly as bad. The fuel pump uses fuel as a coolant, and a lubricant of sorts. If the pump runs dry it overheats, and that can be the end of it or shorten its life. I never go below 1/4 tank. In the end, its all the same amount of fuel used anyways.

[akewlguy]

Wow this is really great!

I never used cruise control and now I am going to use it. 30mpg is more then most 6 cylinders get. I might go 55 for a 110 mile trip and see what happens? Then I will try 65 and 75. Its so hard not to have fun with the peddle.

When I was in the outback of Georgia I drove about 40 miles with light on. In the end I had about a .75 gallon left.

[flanker271]

I never had the guts to drive with light on, not with a V8 anyways. Cheers to all of you who do!

[akewlguy]

Usually I do it when I just drove from some place far away and have to take a pis.. I try to hold until I am about to pee my pants. :)

Hey I was thinking the cars that get 30 are probalby not in New England. Up here we have to many hills. This means the car has to use more gas to get up the hills. So I think 26 may be possible.

[sha4000]

30mpg is not a regular occurrence i can only ahieve this on very long trips and my speed has to be above 90 for a very long time , doing about 80+ i average about 23-24pg with the rpms around 2500. no one is going to average 30mpg on a regular basis

[akewlguy]

I just want to do it once to say it was done in my LEXUS! Just drove about 80 miles at 60 mph and 2000 rpm. Going to see what happens.

[blake918]

In my experience with the LS, the actual speed and a/c usage has very little to do with the fuel econ. I find that my biggest influence on my fuel mileage is how steady I keep the speed...crusie control is a savior.

In a recent 700 mile trip, I had the air set below 70 and set the cruise on 78/79 and turned it off only a handful of times, and I got 27mpg. I can see the gas needle falling everytime I cancel the CC. On a trip like this (I've driven this course several times), I usually get 25.5-26 mpg, but I was on the road late at night, and there was hardly any traffic. I've never had the nerve to go over 520 miles on one tank. lol

[akewlguy]

Just drove at a constant of 60 mph. 80% of the time was on the highway and 20% city.

The result was a little more then 21mpg.

So I think its better to go about 70 with this LEXUS.

[VBdenny]

I admire you kewl if you can drive 100 miles at 55mph. I think I might go nuts if I had to do that. I will have to check my milage sometime. My wife and I cruised down to the Oceanfront in Virginia beach Sunday for lunch. At one point she got annoyed and said how fast are you going? I looked down and said, just about 100. She said well that is too fast, slow down a little so I dropped down to 80 or so. How can I expect good gas milage when it is just so much fun to "get on it" a little? I figure so what, I don't spend a lot on movies, I'd rather run the Interstates.

[Paul Sherman]

Uh, oh

I'm guessing that means I've got a problem.

I'm lucky to break 20 on the highway right now,

figured it was the AC.

Phooey

[Otto]

the best i have gotten is 27 mpg, and they were hilly miles at speeds around seventy,i gained altitude too the whole way starting at 4700 and going to 8000 but lots of up and down. i think my tires were pumped up a little too hard 35 psi. i let some out. its hard going from 35 degrees at 8000 feet to 80 degrees at sea level to figure out what to pump the tires up to.... especially crossing the mojave when its a hundred and ten. i figured i lose 4 psi going from eight thousand to sealevel but i think i get around six psi back from the temp. increase...? i don't know i guess i just keep checking them. 27 mpg's on a v8 with nearly 250k is pretty good i think. its about 21 city but i drive like a grandma.

[HomerTHX1138]

You can avoid cycling the A/C on and off manually by simply putting the temperature control in max cooling and the system in recirculate. Then use the blower speed to adjust/set your comfort level.

NEVER use reciculate if the OAT is below 50F.

In automatic mode the Lexus climate control uses a reheat/remix mode wherein all of the system airflow is first cooled via passing through the A/C evaporator and then a selected portion is reheated via the heater and then remixed with the cooled airflow.

Using max cool bypasses the remix/reheat cycle and results in greatly reduced operational cycling of the A/C compressor.

I have a question: Does the cycling improve mileage? I would think the constant compressor would simply mean a bit more drag, constantly.

Also is compressor life affected by cycling versus constant use?

Thanks.

[corndog]

Neat thread akg! Its fun reading what mileage other folks are getting. I will throw in my 2c worth here since I just returned from a vacation in Lake Tahoe, where I monitered my mileage just for kicks.

I drove 400 miles with 17 gallons(23.5mpg)

Conditions:

I climbed to about 6800' from 50'(and back down on the way home).

Tire pressure unknown.

A/C running almost all the time.

Speeds between 70-80.

2.5 passengers, full trunk and back seat.

I have only owned this car(90'ls400) for less than a month and I have never liked a car so much. On the trip to Tahoe, the car literally did not need to downshift. It only did once because I got stuck behind a Toyota pickup. This thing is made for highways, its amazing. This sounds silly. but I love my car so much im going to get an old es300 for the wife. Lexus may have earned a lifetime customer with this old car.

[nc211]

Lexus may have earned a lifetime customer with this old car.

Hahaha...another one added to the list.. You'll find it VERY TOUGH in the coming years to convince yourself to ever sell, or even purchase a different type of vehicle. It can get very painful if she ever needs a hefty repair, and I'm sure you'll ask yourself if the bill is worth it. You'll test drive other cars thinking it might be worth replacing. Then, one drive after driving others, you'll hand your credit card over to the cashier at the repair shop and be happily on your way. It's just sooooo hard to replace these cars for something that is designed to do the same thing "cruise". Look at CanadaCraig and all of his problems he's had with his. He just purchased a fully loaded 300C with some sort of mega HP package, and yet he is still on the fence about getting rid of his LS. They're addictive as hell.

[MarioC]

19-22 City drivingn with my new baby 91 ls400 and loving every minute of it ^^

Ive been stepping on it quite a bit lately after fixing all the problems I had on the way home with it. Mileage is about what i expected from the V8 and after using 98 octane and the lucas fuel injector cleaner on it it seems to feel a bit peppier. The previous owner took great care of it but he being almost 75 I doubt he ever really stepped on the gas like I have been the last week.

thread hijack, is there any other additive or cleaner that will improve mileage or responsiveness that I can use safely?

-ive never been a believer in slick 50 or any other "miracle" product-

MarioC

[nc211]

thread hijack, is there any other additive or cleaner that will improve mileage or responsiveness that I can use safely?

-ive never been a believer in slick 50 or any other "miracle" product-

MarioC

SEAFOAM...

Run a search for Seafoam and all of it's uses. It's great stuff! It's best to use on an empty tank, pour in, then fill immeaditly to mix it. Then hit the highway for a few hours and let it burn through. I use it every few months right before I go to the beach "130 miles". Great stuff. Works wonders in the oil too, and throttle body cleaning, but you need to read the other threads on how to use it first before messing with it at that level.

Can't say enough good things Seafoam has done on my car's engine operation. Just understand how to use it first if you plan on using it in the oil or intake. Using it in the fuel system is no different than any other fuel additive. Just pour it in, fill up the car, and drive on.