bd3471

Has anyone replaced a component that lead to a huge increase in fuel efficiency/MPG? Currently getting 20 MPG max with all highway driving, about 17-18 combined. I see a few others have achieved 25-30 MPG. Any tips would be greatly appreciated. Bought my '04 LS430 at 140,000 miles, currently at 170,000 miles and not sure if the spark plugs were ever changed. I might try starting there.

Johnhav430

On my LS it was around 27-28 highway when I got it. This year I replaced the air filter and plugs and it had no effect on mpgs. Actually got worse. I am hoping and pretty much believe it's not the actual activity of replacing the parts, it's the type of driving done. I also wonder how many people don't consider the driving conditions. I look at avg mph, and the lower it is, the lower the avg mpg, because it means there was a lot of 0 mph driving, i.e. stop and go.

Are you only getting 20 mpg in pure highway driving? Meaning, you accelerate to 65-70 mph, set the cruise, reset the mpg, and proceed to go 50 miles straight. Will you now only get 20 mpg? If so, I'd be curious too if there is any one factor having a detrimental effect on your mpgs...

Bocatrip

I agree that for the most part, it really is the type of driving that determines your MPG. Even if you do all highway driving, but are driving over 75 mph and are constantly changing lanes and passing other cars, i wouldn't think you would be getting much more than 20mpg. Personally, I only drive (99%) city.....which means I am sitting at lights or traffic getting 0 mpg. Having said that, if I'm easy on accelerating and the traffic is not absolutely horrific I can get 14-15 mpg. Otherwise I'll be looking at 13 or under. It is what it is. I'm driving an aircraft carrier.

Johnhav430

The assumption with me as well, is I reset all the stats, with every fill-up. My brother states he gets 18 with his Ford Raptor. In a brotherly way I called BS (forums say 12 is a more realistic number). So he texts me back and his dash says 18 mpg. We don't know the context. How far did he drive? what does that represent? Did he just reset it, and go 3 miles downhill? Is he a genius driving a 500HP vehicle getting better mpgs than everyone on the internet? nobody can know.

Right now my LS430 says 14.5 mpg and that's over half a tank, so not likely to recover. Context? All city driving and my wife had it too, mpgs plummet when she takes it. There's no egg between the foot and accelerator when she has it, the way there is with me.

kimsey

Get the two o2 sensors that affect performance, and clean or buy a new maf sensor.

Bsavage

I can relate to 14-15mpg city and 18-20mpg highway, I can literally see my gas gauge go down if I’m going 40 + miles also wouldn’t the 01-03 burn more gas cause of there 5 speed compared to 04-06 with the 6 speed trans?

jayclapp

A rather constant 75mph on a interstate will give you 27-28 mpg. Whether you're going up or down in elevation will have an effect as well as wind conditions. The best way to determine a good average is for a return trip going both ways under same conditions.

Ellesse

In my experience the dash mpg rating is always off, not by a magnitude of difference, but off.
Best way to do it is fill your tank, reset the trip meter, and drive until you've drained most of the tank. At the next refill, divide the mileage you've driven by the gallons youve filled, and that will give you a slightly more realistic number (usually close to what the car thinks but at least you'll know if you're off and by how much!)

Johnhav430

What is funny in general (nothing to do with the OP) is that our math skills are poor. I don't mean that you have to be like my mom in the old days, she rolls up to a toll booth, toll is $0.55. She proceeds to give the attendant a single, and a nickel. Talk about confusion, "But m'aam, the toll is fifty-five cents, what's this nickel for?"

Then you have my dad, who could amortize a mortgage with pen and paper, even though even in his time, spreadsheets were all the rage. When I was about my son's age (5) he was trying to explain to me why a V6 is a bad design, and imbalanced. He would tell me the inline 6 is perfectly balanced, and the V8 is not but in practical use it is. I was clueless on what he was saying, but remembered him saying in grandpas day the same car could have a I6, V6, or V8.

Today, no internet = no knowledge. So that broadband goes down, the world stops lol

The posts where people say the range is inaccurate is funny.

With the mpg computer? Man my wife's GM is way off. We're talking it may say she consumed 19 gal, go to the pump, 16. Not even close. But the Lexus is within .3. BMW about 0.0 and 0.1 on a bad day.

bd3471

Close to pure. After filling up and 20 mile highway drive, the best I can do is 20mpg according to the "Tank AVG" which resets after every fill-up. I may get a 1.5-2.0mpg boost if I use Lucas Fuel Treatment. I will try pure highway (65-70mph), no lane changing, and cruise control to see if it makes a difference. I appreciate everyone's feedback so quick! I know this isn't meant to be a fuel efficient car, but i'll still try

bradland

Have you checked your tire pressure recently? Simple and often underestimated when it comes to MPG...

TominPT

Do the following experiment to assess basic parameters of engine health and mpg: drive at a absolutely steady rate of 45 mph in 6th gear on flat level ground, with no wind, and get your instantaneous mpg and get a sense of what the average is over a mile or so. Keep your foot still when you do this as the mpg readout will jump around with the slightest movement of the go foot. Report your results.

I am getting around 31 or a little above, last time I did this test.

If your not getting at least 25 or so, it could be tire inflation (as pointed out above), plugs, air filter or some other maintenance might be lacking, brakes are dragging, coolant temp sensor needs changing, etc.

If you are getting at least 30, your relatively poor mpgs are the result of driving habits and your local conditions, i.e, hills , stop lights, traffic ebb and flow, etc..

My tank to tank average is ~ 25 mpg with 80 % highway, (55-65 mph). City driving brings the average down in a big way.. Mostly rural roads with a few hills and few traffic lights, little traffic, drive with a light foot = good for mpg..

YODAONE

Ruthenium spark plugs;

https://www.clublexus.com/forums/ls-...ark-plugs.html

Vantage007

There is a huge disparity in our cars between city driving and highway driving. While I can easily pull off 30MPG highway on a road trip, if I mix any city driving into the tank, the mileage takes a proverbial dump. If your car is an '04, that means it has the updated six-speed transmission. This means it can theoretically get the best possible mileage of a 430. For the record, my car now has over 175,000 miles and mileage hasn't really changed at all. I'm up to date with maintenance.

Johnhav430

There's a reason why "enhancement" products exist. Because people, usually men, think that they will fill some sort of void for them.

Another one would be, "How can I lose weight without exercising or reducing my consumption?" There are products for that too.