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I have taken my newly acquired 2005 LS 430 to an amazingly highway fuel efficiency level by simply doing the following things available to any LS 430 owner.

1) Aired up the OEM Dunlop SP 5000 tires to 35 PSI with Nitrogen to stabilize pressure against

temperature variations.

2) Replaced stock air filter in air box with exact fit K&N air filter from Amazon.Com.

3) Replaced stock Denso plugs with Denso Twin Tip Iridium plugs from Jegs.com. Visit Densott.com/iridium.

4) Replaced stock Lexus Synthetic blend oil with Royal Purple 5W30 100% synthetic oil in crankcase.

5) Replaced stock Lexus differential oil with Royal Purple 75W90 100% synthetic oil.

Here are my ACCURATE results with premium fuel 93 octaine Tip Topped Up at beginning and end of trip and miles driven divided by gallons pumped on same route 3 different times.

1) Distance 96 miles, 52 degrees F, 60 mph mostly some 65 mph all on cruise, 2.449 gallons,

pumped 31.4 MPG!

2) Distance 99 miles, 66 degrees F, 65 mph on cruise, 3.449 gallons pumped, 30.6 MPG!

3) Distance 100 miles, 66 degrees F, 55 mph on cruise, 2.99 gallons pumped, 33.4 MPG!

Looking forward to changing the stock transmission fluid in the sealed transmission soon with Royal

Purple 100% synthetic with the anticipation of more, if only slight, improvement in MPG.

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Wow, 20% extra for premium...

Here in northern CA, the uplift for premium is 6%. Historically it's always been around 5-7% around here.

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I have taken my newly acquired 2005 LS 430 to an amazingly highway fuel efficiency level by simply doing the following things available to any LS 430 owner.

1) Aired up the OEM Dunlop SP 5000 tires to 35 PSI with Nitrogen to stabilize pressure against

temperature variations.

2) Replaced stock air filter in air box with exact fit K&N air filter from Amazon.Com.

3) Replaced stock Denso plugs with Denso Twin Tip Iridium plugs from Jegs.com. Visit Densott.com/iridium.

4) Replaced stock Lexus Synthetic blend oil with Royal Purple 5W30 100% synthetic oil in crankcase.

5) Replaced stock Lexus differential oil with Royal Purple 75W90 100% synthetic oil.

Here are my ACCURATE results with premium fuel 93 octaine Tip Topped Up at beginning and end of trip and miles driven divided by gallons pumped on same route 3 different times.

1) Distance 96 miles, 52 degrees F, 60 mph mostly some 65 mph all on cruise, 2.449 gallons,

pumped 31.4 MPG!

2) Distance 99 miles, 66 degrees F, 65 mph on cruise, 3.449 gallons pumped, 30.6 MPG!

3) Distance 100 miles, 66 degrees F, 55 mph on cruise, 2.99 gallons pumped, 33.4 MPG!

Looking forward to changing the stock transmission fluid in the sealed transmission soon with Royal

Purple 100% synthetic with the anticipation of more, if only slight, improvement in MPG.

Very Interesting read .....I am in the same boat ...just acquired an used 2006 LS 430 and wondering what can I do to boost mileage...so thanks a bunch upfront for sharing .....my only question to you .....did you do all these changes one at a time and checked the mileage or the improvement is an output of the combined change?

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I didn't make the above tests until all of the items except changing the transmission fluid were done.

I realize that the approx. 100 mile range above is open to discussion as to exactly what I now get on the highway so a much longer highway trip to Mobile, AL from Baton Rouge, LA and return the weekend of February 8, 2015 may settle any argument.

GOING: 239.8 miles,68 degrees F, 65 MPH on cruise, no A/C, 4.04 hour duration, Average 59 MPH, 8.066 gallons, no head or tail wind, 29.7 MPG !

RETURN: 240.6 miles, 73 degrees F, 70 MPH on cruise, A/C 1/2 of trip, 3:50 hour duration, Average 63 MPH, 8.082 gallons, no head or tail wind, 29.8 MPG !

I have a history of driving Diesel powered cars and always striving for milage so it was only natural that I'd try it with the LEXUS. Given the current low price of gasoline my current approx. 7 cents per mile fuel cost on the LS 430 is remarkable!

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The last time I drove to Vegas I remember gassing up the LS430 and getting back on the highway and the trip computer returned 27.4 mpg; this was in the summer cruising around 70-80 mph; in 100 degree heat with the AC on refrigerate.

2004+ cars had the 6 speed transmission which I think resulted in slightly better mileage as the 6th gear was higher; so 28+ mpg seems reasonable. The trip computer tends to be optimistic so you may be seeing a real benefit; but the mpg in these cars for their size and power is remarkable out of the box.

Generally using regular gas lowers the mileage (and the car feels slower) with Premium being such a small premium here in SoCal I figure the reduced mileage makes it a wash.

Honestly I got the biggest lift in mileage when I replaced the spark plugs and cleaned out the throttle body; in my mixed commute mileage went from 19 mpg to 21/22.

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Just to be clear my 29.7 and 29.8 MPG results were calculated by dividing the miles driven by gallons pumped. In each case the fuel was topped off at the beginning and end of the trip. My wife and I were in the car with luggage going and added antique purchases in the trunk on the return trip.

In both cases the trip computer was not optimistic as it showed in the high 28 mpg range.

In my first post regarding mileage I reported replacing the plugs with Denso Twin Tip Iridium's, see Densott.com/iridium, which I believe gave me +1.5 MPG over the stock Denso plugs.

You mention temperature which in the previous tests I suspect was slightly detrimental to my results as temps were on the cool side. I look forward to this summer when I can run the milage test SOLO at +90 F, no wind, with the A/C blowing at 70 MPH on Interstate 10 and achieve the expected 30 MPG which I am clearly inching up on!

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thanks all for the enlightening and educative(at least to me) discussion above ....wondering whether tire selection will add any to the mileage(say low rolling resistance...etc..) though the heavy the car is ....not sure what the ding on safety that would be .....

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Yes, low rolling resistance tires are certainly a meaningful part of the high MPG game, and they don't undully compromise safety, or they wouldn't be sold.

The 2005 LS 430 I'm getting the super highway MPG out of was purchased in early November, 2014 from the Baton Rouge Lexus dealer with only 33,500 miles on it. It had been owned by an 84 year old man since new, who replaced the tires with OEM Dunlop SP 5000 from the dealer when they got to be 10 years old, even the SPARE.

I trust these tires are low rolling resistance tires as when I let off the gas there is no immediate sensation of deceleration what-so-ever. To test it I let off the gas at 60 miles per hour on level terrain and coasted a full mile before coming to a stop.

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Naval air...your case is almost same as me...got my 2006 from a 80 yr old lady for whom it was getting unmanageable. ....with 50k miles on it.

given this one has one of the lowest wind drag....does its great coasting is a function of that or lrr tires?

Also the OEM Dunlop sport is a lrr tire?

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I didn't find when looking on TireRack.Com that the OEM Dunlop SP 5000 was specifically a LRR tire. I believe however that my airing up to 35PSI reduces the rolling resistance of the tires.

In reading about LRR tires the ads usually suggest the the FUEL SAVINGS will be realized over the life of the tires and won't give you the immediate and measurable improvement of from +3-5 MPG I gained by installing a K&N air filter in the air box and replacing the stock Denso plugs with the Denso Twin Tip Iridiums.

Unmentioned in my previous posts regarding high MPG results was the fact that I used the McGuires clay bar kit to restore the finish to a glass like surface, read SUPER SLICK!. That plus the fact the the car has a inherently low coefficient of drag all worked to the good.

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I did a quick search of our data base regarding other postings on LS430 gas mpg. There doesn't seem to be a shortage of ideas on how to reduce the outflow from your wallet. LOL

Paul

http://us.lexusownersclub.com/forums/index.php?s=37ca08f251f4f830f342aca1db8e152a&app=googlecse#gsc.tab=0&gsc.q=ls430%20gas%20mileage

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I remain highly skeptical of the claims. Too many unknown variables and very small sample sizes (several gallons at a time) easily leads to readings on the high side. That being said, the LS430 does get pretty amazing mileage for a larger car.

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I like Naval Air's post. I do not doubt any of the reported results on this thread. I made some modifications on my Ford F-350 diesel and have gotten 24 mpg out of a one ton truck.

What is not talked about much in addition to lubricants, spark plugs and air cleaners is driving style. I shift the auto trans with my right foot by letting up on the fuel. The faster you accelerate the more important that is. Watching the tach is something many people don't do enough of especially in the mountains. I like to accelerate slowly much of the time and slow down well in advance of stop lights. Using cruise control helps on the highway. All of these things contribute greatly to better mileage.

I have owned a 2005 ES 330 for only a short time. The first thing I have done is change out the Denso AC with a K and N and immediately noticed better performance. Next comes syn oil in the crankcase and trans. Then sp plugs. These seem like the logical order to proceed. Thanks for relaying your experiences.

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