Dean2

Thought I would pass on some things I have found that improved the gas mileage on my GS 430.

First off, I manually track every fill, miles driven and maintenance performed. I do not rely on the car displayed mileage calculation though it is fairly close in terms of Klms/Litre. What isn't close is when the miles left to go shows zero, I actually still have over 80- miles or 140 Kilometres worth of gas.

One - I always drive the car in sport shift mode with the ECT power function on, unless the roads are icy. This improves city and highway mileage about 2 miles per gallon on average.

Second, there is a difference in gas mileage using regular versus premium gas. I know many people say there is no difference but in judiciously tracking and trying over many different terrains I definitely see a difference. It about pays for the 10% price difference but the car also performs better on premium, particularly at altitude. The premium gas averages 3 mpg better mileage in town and over 5 mpg better on the highway. So more noticeable on the highway and even more noticeable if the area you are travelling is at higher elevations and has lots of hills. I see no difference in the mileage of the various brands pf premium gas. I get as good gas mileage on Costco gas as I do on Shell or Esso.

An example that minor maintenance can make a big difference: I changed the Iridium plugs at 138,000 Klms. They were supposed to be fine for another 30,000 KLM but I wanted to see what the old ones looked like. I immediately picked up 2.5 MPG in town and 6 MPG highway with 3.5 mpg better on average. This is the best gas mileage the car has ever delivered since I bought it at 50,000 klms and started tracking all of the details.

There were no signs the old plugs weren't working perfect and they looked fine. The Average before plug change 24 mpg (Imperial Gallons). Max 28.52 mpg, min 23.2 mpg. Since the plug change Average 27.57, max 33.35 min 25.57. All of these are monthly figures that represent a mix of highway and city driving. City driving the car runs about 26 mpg now and highway from 31- 33.35 mpg at 120 KPH depending on how hard I am driving and how much hills there are in that area of the mountains.

For the past 6 months I have driven this car 6930 Klms, used 710.022 litres of gas at a cost of $730.49. Overall Average fuel mileage is running 27.57, with a min of 25.23 mpg and a maximum of 33.35 mpg.

I love this GS 430. It handles great in the mountains, has lots of power for passing on twisty 2 lanes and gets great gas mileage in a very comfortable car with lots of room for passengers and baggage. I will definitely get another when this one miles out.

Hope this info helps others with their mileage.

tcr101

iTrader: (2)

What is your average speed for highway? Do you ever pass 2000rpm? Best mileage I've ever pulled from the gs430 was 27mpg hwy and in my gs350, i've pulled low 30s on the hwy.

Dean2

As I said above. I average 120 K or 70 miles per hour on the highway. I do not drive the car to maximise mileage, I drive it for the fun factor. Most of the roads are mountain two lane with lots of passing required. Also, I believe it is good to run the motor up to 5000 rpm or better, both for the good of the car and for the fun it is. The mileage I get is strictly an output, not a goal, beyond keeping the car in top trim.

One other thing to remember is Imperial is 11% larger than U.S. Thus 33.5 mpg Imperial is 30 mpg where you are.and 26 mpg is 23.12. Thus my current average mpg would be 24.5 in U.S.. terms for combined city highway with about 60% City.

Dean2

I was really hoping this thread would start a discussion of other maintenance or things like changed wheels and tires items that showed gas mileage gains. Surprised there is so little comment.

illjuan3

When you say you use the manual mode what do you mean? Are you shifting to higher gears when in normal mode it would coast in a lower gear? Or are you doing other things as well?

Dean2

I use the "sport shift mode" also called select shift by some,, with the EDT power button (raises the shift points and brisks up throttle response) on and the sport ride mode (tightens the suspension) engaged. I manually shift the car rather than let the car do the shifting. I downshift approaching stops, start out in 1st or 2 nd depending on traffic and roads and up shift to 4 th for around town as the revs get where I want them. By manually shifting I can shift at a higher RPM without having to accelerate briskly to raise the shift points. Up-Shifting at 4000 to 4500 rpm around town improves the mileage as long as you accelerate at a normal pace. Even in sport shift you can leave the car in 4th gear and let the car do the shifting and this will still result in better gas mileage, though not as much of an improvement as manually shifting the gears. I have found that not letting the car get into 5th or 6th gear under 45 miles per hour improves overall mileage around town.

Keeping the rpm up on hills and on curves when highway driving also results in lower gas mileage. Allowing the 8 cylinder to lug along at lower rpm uses more gas when there is work to be done. On flat ground lower RPMs are better than higher for long distance cruising and cruise control improves gas mileage on long straight flat stretches.

Hope this helps clarify.