2006 Lx Mpg Questions

[DB S600]

Hello:

I am the owner of a 2004 LX and I feel - as of recently - that my MPG has gone down and that I am refilling the tank all too often. In fact, I have always felt that the tank of my vehicle was insufficient because prior to the LX I had a 1999 Denali - and I didn't recall refilling as much as I did and currently do with the LX.

I have a few questions:

1. Is there any recommended way to improve MPG on this vehicle <-- I know, I know this is probably the magic question for everyone these days, but anything in particular for this vehicle. I have 35k miles on the truck and have performed all routine maintenance

2. Has anyone heard of adding an extended gas tank? Anything that would not be obtrusive to the interior of the vehicle. Something to compensate for how much gas this think actually eats - so that I don’t have to refill so often

3. I know that the manual says that premium should be used - and I have used this octane thus far. But how about a lower octane fuel? I know too that this might cause a decrease in MPG - but can this be substituted without damaging the vehicle / engine?

4. Would adding a rear spoiler improve MPG - or is this simple a styling cue?

and one last one... 5. I know that the 2006 has a revised engine management system (increased horsepower) - but do the '06's also come with improve fuel economy?

Thanks so much! And insight would be much appreciated!

JD

[CJAsis]

I have a few questions:

1. Is there any recommended way to improve MPG on this vehicle <-- I know, I know this is probably the magic question for everyone these days, but anything in particular for this vehicle. I have 35k miles on the truck and have performed all routine maintenance

2. Has anyone heard of adding an extended gas tank? Anything that would not be obtrusive to the interior of the vehicle. Something to compensate for how much gas this think actually eats - so that I don’t have to refill so often

3. I know that the manual says that premium should be used - and I have used this octane thus far. But how about a lower octane fuel? I know too that this might cause a decrease in MPG - but can this be substituted without damaging the vehicle / engine?

4. Would adding a rear spoiler improve MPG - or is this simple a styling cue?

and one last one... 5. I know that the 2006 has a revised engine management system (increased horsepower) - but do the '06's also come with improve fuel economy?

Thanks so much! And insight would be much appreciated!

JD

1. Keep your tires properly inflated. Keep your speeds down. Our LX's onboard computer shows that we get much better MPG at 55 - 65 mph than 65-75. The aerodynamics of these big SUV's absolutely blows so anything over 70mph and you're sucking gas down like a !Removed!. You can also try taking the third row of seats out if you don't use them often as extra weight hurts gas mileage in city driving.

2. Don't know but I'm sure it's been done. Try IH8mud.com for this one. That forum is full of a more hardcore group of offroaders and if anyone's done an extended tank... it would be there.

3. You can use a lower octane fuel w/o hurting the vehicle in almost all conditions. Your vehicle's onboad computer will !Removed! timing to prevent knocking. But you will negatively impact performance and you will likely get worse gas mileage (esp. on hot days with the AC on, etc.). I've not tried this yet with our LX as I think the results would be the same but I can tell you that our old RX300AWD consistently got worse gas mileage when we ran low or mid grade gas vs. premium gas. That was on multiple tanks over roughly the same driving scheme (commuter to and from work in mixed driving).

4. I can't answer that because we bought ours with the rear spoiler. Again, past experience only, the rear spoiler goes a long way towards helping keep the back window clear so it's doing something to airflow. I just don't know if that improves or hurts MPG.

5. We now have just under 3,000 miles on our 2006 LX. This is our daily driver and so our driving is pretty much consistent for traffic patterns, routes, etc. Our first tank we only got 13mpg. That improved with every tank until the vehicle had about 1,000 miles on it. We are now getting between 14.5 and 16 mpg with each tank depending on whether we take the toll road or not (our local toll road has two huge hills which require a kickdown to 4th so between that and the near autobahn speeds (80mph seems to be the cruising speed) we notice that our avg. fuel consumption is defintiely affected every time we take the toll road.

Overall.. I can appreciate your concerns for fuel mileage since I don't enjoy spending upwards of $80 every week and a half to fill our tank either. But in my mind getting roughly 15mpg for a full size, 7+ passenger, permanent AWD SUV isn't bad at all. It's world's better than my neighbor is getting in his silly H2 Hummber (8-10mpg) and almost as good as another neighbor is getting in his Acura MDX (17-19mpg).

[Jim_Chow]

3. You can use a lower octane fuel w/o hurting the vehicle in almost all conditions. Your vehicle's onboad computer will !Removed! timing to prevent knocking. But you will negatively impact performance and you will likely get worse gas mileage (esp. on hot days with the AC on, etc.). I've not tried this yet with our LX as I think the results would be the same but I can tell you that our old RX300AWD consistently got worse gas mileage when we ran low or mid grade gas vs. premium gas. That was on multiple tanks over roughly the same driving scheme (commuter to and from work in mixed driving).

I've tried this in my '03. Fuel economy was 14.5 w/ 87 octane, 17 w/ 91 octane, mix of city/hwy driving but mostly city, AC set to low but running most of the time. So that's 17% better fuel economy for about 7% increased cost in gas...seems like a good deal to me. There's an article in the June issue of LC magazine addressing how to improve fuel economy. Off the top of my head, I think they say to use high octane gas over regular (don't know what octane they're referring to, as different countries have different octanes), clean/change the air filter, keep tires inflated, make sure spark plugs are in good shape (they change iridium's at 60K mi), injectors are clean. There are probably other things...haven't looked at it carefully enough since I just got it in the mail last night.

The engine generally won't knock w/ 87 octane, but you lose a lot of power and need to use a lot more throttle just to accelerate at the same rate or maintain speed. That's where most of the savings is coming from. It felt like I had 30+ hp more w/ 91 octane over 87 (I live at 2500-3K ft, low humidity air). With 87, the LX wouldn't accelerate any faster than my 86 4runner, and that's a 116 hp 4-cyl 22re engine w/ modified exhaust/cam pulling at least 3500-4000 lbs of weight (250 lbs of body armor, lift, bigger tires, etc.), so in my mind, that's totally pathetic!

[cthronson]

Pardon my ignorance, but what is "LC Magazine?"

[Jim_Chow]

Pardon my ignorance, but what is "LC Magazine?"

Landcruiser magazine. Click here.

[DB S600]

thank you for everyone's input -

ive removed the third row seats and havent really seem any difference in gas consumption. also ive asked my dealer about the rear spoiler - they say that its more a less just a styling feature and that it keeps the rear window clean - for some reason they were really trying to tell me not to have it installed because rust might form from the need for drilling (b/c its not from the factory) i was really surprised that they didnt want to make a few $$$. what i think ill do is as a new aftermarket air filter and see if there is any difference - ill keep the board posted - thx

[pagemaster]

Hello:

2. Has anyone heard of adding an extended gas tank? Anything that would not be obtrusive to the interior of the vehicle. Something to compensate for how much gas this think actually eats - so that I don’t have to refill so often

3

Yes. The Lexus LX470 sold in New Zealand has a 96 litre main tank and a 45 litre sub tank. Total litres come out to 141.

[slabman]

I have a 1999 model and have religuosly kept track of every gallon I've put into that car(87 octane) Avg. mpg has been 15 in winter and 14 in summer with A/C on, stretching over 6 years. Over the past few months it has dropped down to 13 and was told by my service guy it is likely the 15% ethanol blend in today's gasoline. I know ethanol is a little lower in btu content, but was surprised at that much difference. So not only do we pay more/gallon, it doesn't get us as far. BUMMER! I still love the car!

Two months ago I decided to try 93 octane and saw no difference from 87 octane but the performance seemed better. Not sure I can justify the added expense this way. Back to 87 octane for me.....

PS....Someone please explain to me why adding another tank would improve fuel efficiency.

[Jim_Chow]

I just completed my first road trip in my 03 LX from So. AZ to the S. Rockies. For the 1580 miles, I got 19.3 mpg running only chevron 91, cruise control set to 69mph on the interstate [2200-2300 rpm] (calculated by the odometer readings and amount of fuel used). Worst mileage was 16.86 mpg in traffic in Taos, best was 20.9 mpg from Socorro to Taos. This is with a loaded vehicle, 3rd row seats removed, everything stock, tires at 32psi cold pressure. BTW, I push the cross bars on the roof rails as far back as possible...minimized drag since it's turbulent further back. The AHC set to sport helps in the mountains, as you don't have to brake as much on the downhills. Oh, yeah, I changed the engine oil to Mobil 1 delvac 5w40 before leaving. I've used it before in my 4runner and honda and it improved fuel economy by ~10% over Mobil 1 10w30 and dino 10w40.

[slabman]

Jim, I'd say that's spectacular. I think the oil's the key here...and then give yourself a little credit for the light throttle? I'm wondering if Toyota approves of this weight oil in their engines? I mean, we could prob. add some kerosene to lighten the viscosity, but I'm sure they'd look at that with disdain.

[Jim_Chow]

Jim, I'd say that's spectacular. I think the oil's the key here...and then give yourself a little credit for the light throttle? I'm wondering if Toyota approves of this weight oil in their engines? I mean, we could prob. add some kerosene to lighten the viscosity, but I'm sure they'd look at that with disdain.

5w40 full synthetic (group IV/V) basestocks has a much HIGHER viscosity than dino 5w30. Dino 5w30 is basically a 5wt oil w/ polymer additives that make it behave like a 30 wt oil when hot (the molecules "uncurl", but get sheared from high rpm's/heat, reducing the effectiveness). OTOH, a full synthetic 5w40 is a 40 wt oil that behaves like a 5wt when cold (doesn't get thick). So a higher viscosity oil is definitely going to give more protection than dino 5w30. BTW, overseas (Japan/Australia), the LC/LX is spec'd w/ 10w30 dino. The 5w30 spec in the US is because automakers can artificially improve their CAFE results by using a thinner oil, but the US gov't requires that they recommend/sell the oil grade used in the tests, hence the 5w30. I would not use any 5w30. I have a '86 4runner w/ 195K mi that used 10w30 and 10w40 for the first 145K mi, then I switched to Shell Rotella T synthetic 5w40 (pretty thick stuff). Still runs great, gets great fuel economy.