SirKronan

Hello, fellow IS owners! I'm new here. Will post pics and specs to the rollcall thread when I have some good pictures to share!

2012 IS 250 AWD - So far loving it!

One thing I miss from other cars I have owned: The ability to keep it in high gear and prevent unnecessary downshifts!

I'll be honest ... I am not THRILLED with my highway MPGs so far. I realized after the fact, that the 30 highway/21 city mpg figures I googled before purchasing were for the NON-all wheel drive variant. Driving the speed limit in 50-60 degree weather on mostly flat, relatively nice roads on my 52 mile (one way) commute to work, I am averaging 22mpg (on the computer AND at the pump). I am not in PWR or SNOW mode. I have great tires, and the engine seems to be running quite nicely. No aggressive driving, as I really want to get the best MPGs possible on my work commute. I always shudder when I see the MPG dramatically and instantly DROP when I am barely going up a measly incline that ends in a few seconds. This happens frequently (and annoyingly) throughout the drive. The speed limit is 70MPH, and that is what I set my cruise control to.

Even in S mode, I cannot paddleshift it into 6th gear. From what I've read on this forum so far, it seems like your paddle shifters and S mode shifting merely set the highest gear limit, rather than making it shift.

In another thread, I saw someone ask about putting it in 5th or 6th gear at 40mph in town, and the responses where quite blunt and direct to that OP. I am NOT trying to drive 40mph in 6th gear, but for as flat as the drive is out to work, it is absurd the amount of wasteful downshifting this thing does. It's smooth as butter when it does it, but I still see my MPG drop and my RPM jump up.

I am coming from a 2010 Mini Cooper Clubman S - an absolute JOY to drive ... when it wasn't in my GARAGE!! That car let me keep it in high gear for minor hills, only overriding me when it absolutely HAD to. Same with the Jetta I used to own that had manual override shifting on its automatic transmission.

My old Civic with the WEAKEST Civic engine and 220,000 miles on it can stay in 5th gear on that same drive and has zero trouble on any of the very mild ups and downs.

I am new to Lexus (owned two Toyotas in the past) and hoping there is a fix of some kind for this. I appreciate ANY and ALL help from all of you!

Thanks!!

flowrider

iTrader: (9)

According to the EPA, your figures seem to be low:

https://www.fueleconomy.gov/feg/noframes/31659.shtml

Lou

nosurprise

iTrader: (1)

When I don't step hard on the gas, the car will be in 6th gear at or above 40mph. It will stay at 6th gear until it drops to 35mph. It will stay at the 5th gear until 25mph if you're coasting. The car adjusts a little bit depending on your driving style. If you drive aggressively, it will down shift a lot. You can pull the battery for 10 minutes or so if you want it to relearn your driving style.

gompka

iTrader: (6)

I have the same experience as nosurprise above, if i drive easy and set cruise control I will be in 6th gear. I have an is350 and on all highway driving I am able to get over 30mpg on calm days. One thing i do notice is mileage goes way down when its very cold and when using winter blend gasoline.

mcomer

At the risk of opening a can of worms that has been debated time and again in other threads...OP, are you using Premium Fuel?

SirKronan

Thanks for your response, Lou! I agree!!

That is a good suggestion, since I am the new owner. I might have to give that a try!!

I don't believe I'm using winter blend. How would I know that the gas stations switched? I see no signs or changes at the pump...

That is a good question, and absolutely I am using only premium fuel. 91 is the highest available here, but I have put it in every time.

i must say, i filled my tank again last night and added some injector cleaner. Drove the same drive today and am averaging 29mpg, all highway. It is the same drive I made with the same temperature and weather. I'm definitely happy getting 29 as a tank average. That includes driving through town to get to the highway, and my 52 mile drive to work.

Does injector cleaner really make THAT much difference? I also bought Exxon premium this time. Last tank was Sam's Club premium I believe.

Thanks everyone for the responses!!!

2013FSport

iTrader: (2)

350 owner 60%creeping city traffic/40% hwy gets 22mpg.
Open road flogging it a bit and it still gets 26mpg.

Check your air filter
Clean the MAF
Verify no vacuum leaks
Throw some new plugs in it
Maybe a can Techron Injector cleaner... Not gonna help much, but....

mfdif

I have a 07 250 AWD and am averaging 23.5mpg with 80% hwy and 20% city. I cruise at 80mph and daily get it past 5k a couple times at on/off ramps and turning into traffic. I'd say you're a tiny bit low, but not too far off.

timmy0tool

iTrader: (7)

try driving the car in ECT PWR mode!
though it's been known not to greatly affect MPG it does have an effect in shift points.

SirKronan

Thank you! I have put in an injector cleaner. Seems a little better. I will check all those other things.

One thing I don't get, I set the cruise at 70mph and got it to average 29mpg on the highway, but Idaho interstates have an 80mph speed limit. This thing gets significantly worse mpg at 80mph, but I will be cruising at that speed in the future when I make long road trips. Wish the extra mph didn't kill your mpg so badly! My Mini Cooper Clubman S was perfectly content at 80mph. Got literally identical mpg to driving 70, which was also surprising because I expected it to be at least a little bit worse.

You're not the first person I've seen suggest that. I'll give it a try!

I do absolutely love this car. Everything is so smooth and comfortable and refined. I've honestly never owned anything quite like it!

attached is a pic of possible mpg with premium fuel, injector cleaner, driving 70mph on the highway combined with gentle in town driving. This is my typical drive from home to work and back again.

Best round trip MPG so far.

The unnecessary downshifts are still somewhat annoying...