Tony1M

This afternoon my wife and I were returing to Edmonton in our '05 LS430 from a trip to Lake Louise. When the low-fuel indicator came on, the distance remaining display said we still had over 50 miles to go. But the fuel-gauge needle was getting uncomfortably close to the "E" mark, so we stopped to add a bit more fuel in order to get us back home "strees free" so that I could take the car to a place where I usually fill up.

Anyway, after doing several preliminary searches on the subject, I couldn't find answers to two intimately related questions:
1. How accurate/reliable is the distance remaining indication?
2. How much fuel is left in the tank when the "low fuel" indicator illuminates?

Thanks.

GLIDESUL

Good question, I drove on e low fuel level in the ls but for only bout 15 miles sweating then filled up. But far as how many miles or gallons are in there its gotta have at most 3gallons when lit up, just my guess.

caddyowner

This is starting to sound like some of the hybrid forums where they take pride in how many miles they can squeeze out of a tank of fuel. (Some of results of hypermilers with a HS250 are pretty stunning.) IMO, if the low fuel light comes one, I've failed to correctly monitor my fuel situation. I used to commute into downtown Detroit and my 50 minute commute could be 2.5 hours for almost no reason aside from gawkers. In the summer, I target fill-ups at 1/4 tank and at 1/2 tank in the winter. Yes, I may stop for fuel a bit more often and my MPGs may suffer a bit by hauling around an extra 40-50 lbs. of fuel, but I don't like to feel nervous about running out of fuel.

Jabberwock

I am pretty sure there is at least 2 gallons remaining when low fuel light comes on - so min of 30-40 mile range depending on conditions.

Another reason to avoid running out of fuel is the electric fuel pump on current cars is sensitive to being run with no gas - it can burn itself out if it is run on an totally dry gas tank for even a relatively short period..its not instantaneous destruction by any means, but its a good (less obvious ) reason to avoid running totally out of gas.

Tony1M

Thanks for the replies, folks.

The reasons that I like using a particular gas station (Costco) is that they have a storage tank that is within three years old and their high-test is the least expensive by far and, therefore, by far the freshest. For example, yesterday at Costco it was $1.14/L, while the high test at Lake Louise was approximately $1.37/L and Banff and closer towns were at least $1.27.

We filled at Costco before leaving for Lake Louise and, after various side trips, had plenty of fuel to make it to Calgary, where I added an amount of V-Power at Shell that the distance remaining indicator told us would get us to Edmonton.

Upon approaching Leduc, just south of Edmonton, after noticing the fuel gauge and the little illuminated fuel pump next to the "E", my wife started to lose more than a bit of her composure, but, as I said, the distance remaining idication was still around 50 miles. It was maybe 20 to our destination. (We imported the car from the US last year, so the indicator is in miles rather than km.)

Highway 2 is pretty smooth and level from Airdrie northward to Edmonton, so the distance-remaining vs. actual-distance-to-go ratio actually improved as we got closer and closer to Edmonton.

If there really are at least 2 gallons remaining in the tank when the low-fuel indicator comes on, I believe that the distance-remaining data was correct and we would have made it to Costco for a fill-up, but we stopped in Leduc and added $5 of high test just to calm the passengers in the main cabin.

Again, thanks for the advice. I'll give Lexus a call today and ask if they have any further information on how much gas is in the tank when that indicator comes on. If they do, I'll post it.

caddyowner

Speaking of calming the passengers in the main cabin, good info here and in the other links on fuel management.

http://www.experimentalaircraft.info...nagement-3.php

ancdmd

I routinely have the warning light come on and then a short time later the LOW FUEL message comes on at the 35-mi remaining point. I've had the needle on the gauge go far below the last notch. I estimate there's a 50-mile range left once that orange warning light comes on. As long as you're just doing highway cruising it's pretty accurate.

Tony1M

ancdmd, thanks very much for posting your valuable experience. I will take it to heart.

I called two Lexus dealers here in Alberta and Lexus USA. Here are the rather unsatisfying results of those phone calls:

1. Lexus of Edmonton claims there are 5 litres of fuel remaining when the low-fuel indicator comes on. The instant I heard this, I didn't believe it, because we would certainly have run out of fuel yesterday.

2. Lexus of Calgary claims that the low fuel indicator is conservative to the extreme. When I mentioned that our distance-remaining indicator displayed 80 km (50 miles), he said that this was "quite possible". In our car, at least, this means a minimum of 2 gallons (7.6 litres) remaining.

3. When I posed these questions to a person at Lexus USA, the first thing that the person said upon hearing them was "those are great questions. I'll check that out for you right away". It went downhill from there. After a considerable time on "hold", she said that Lexus "does not publish" either the amount of fuel remaining in the tank when the low-fuel indicator illuminates, or the plus-or-minus accuracy of the distance-remaining data. This "specialist" said that the amount of remaining fuel and distance were both dependent upon the type of terrain that one was about to cover (no kidding?), so it was "best to just fill up the tank". She said that "someone, somewhere in Lexus must know the answer to these simple questions, but we do not have access to those people". (Translation: This is as far as I'm investigating and I'm not giving you any avenue to pursue the matter further, either.)

Well, I still want to know the answer to these questions, so when this present tank of fuel starts to dwindle, I will answer these bone-simple questions for myself. (I did this on my '84 Yamaha Venture Royale a few years ago, too. When the low-fuel light illuminated on that bike, the one-gallon reserve would move you at least 40 miles further down the road. Yikes, get to that gas station ASAP!)

Below is how I'll solve the great mystery.
1. Place a full, 20-l jerry can and an empty, calibrated-graduated 2 litre pop bottle in the trunk. I'll calibrate and mark the bottle by using our digital kitchen scale. I'll mark the side of the bottle at 250-ml (250-gram) points.

2. When the low-fuel indicator illuminates, I will take note of the odometer and distance-remaining data.

3. As the tank approaches bone dry, I will drive the car in a level, ultra-low-traffic area until either the engine stops dead or starts running strangely, indicating an imminent stall.

4. I will then take note of both the distance-remaining and odometer data.

5. To obtain maximum accuracy, I will transfer a small quantity of fuel from the larger jerry can to the graduated bottle. As I slowly re-fill the car's tank from the bottle, I will take note of the point at which the illumintated low-fuel indicator turns off.

When the above steps are completed, I'll have a very good idea of how much fuel is in the tank when the low-fuel indicator illuminates (turns off), as well as a pretty good idea of the accuracy of the distance-remaining data.

I'll post the results as soon as I obtain them, but don't expect them soon. We own two cars. Last year we filled "the boat" a grand total of three times. (The car's odometer went past 19K miles during this last trip.) The last fill-up may very well last a couple of months.

LRoy430ul

iTrader: (1)

I ran out of gas twice in my 04 LS within the first yr of owning it. The low fuel indicator came on both times and the distance remaining was bout 30 miles. Since then I knew the indicator was wrong. From now on if the light comes on, I make sure to fill up within the next 10 miles or so.

caddyowner

We purchasers of low-mileage used cars who then pile on the miles love first owners like you. Keep up the good work.

CarGuy89

+1 The cars with the lowest miles always catch my eyes first

parkerjs

I certainly wouldn't trust the range indicator to be better than 10 or 15% or 20 miles, whichever is greater. I interpret the light to mean 'stop and get gas within the next 20 miles'.

mndaves

Since the amount the tank holds full is known (22.2 gallons), couldn't you ride around the block where your Costco is and when the light goes on pull right in and top off, then subtract the volume purchased from 22.2?

Might save some stress on the engine... Of course, it might also attract local law enforcement.

Tony1M

Good suggestion, but after my experience on the phone with Lexus today, I would take that 22.2-gallon capacity with a grain of salt. Maybe they publish a capacity that is deliberately lower than actual for the "safety and convenience" of the customer. Besides, is that published capacity "up the pipe" to near overflow from the filler tube, or "first shut-off" of the nozzle? (And how deep is the nozzle inserted for that first shut off?) I know that when I fill, after first shut-off of the nozzle, I continue to add a fair bit of fuel, although I haven't kept track of exactly how much that ends up being.

When I'm finished doing my little procedure, I'll know what I want to know about our car with more than adequate precision -- information that even Lexus dealers and "specialists" either don't know or are unwilling to reveal.

AlexusAnja

From my experience, once the light comes on, you have atleast 42 miles of local driving (traffic lights, smooth driving, NOT stop n go traffic) left. I'm averaging 18 mpg in condition I had driven in, so if you figure same for highway (24 mpg) then it's easily an extra 50-56 miles left.

And even after I had driven the 42 miles, I was only able to fill 20.9 gallons or so until the pump kicked off. So, there's still over one gallon of fuel left which theoretically would go another 18-22 miles, but you would not want to run it dry.