Factory suggests 100K for the change, one Lex tech said don't replace until they error out. My thought is that by the time they may error out they'd have been telling the EFI-ECU to run rich or lean. The rich scenario I didn't like especially in a rich condition that may kill the cats. Gas at $3.45 isn't cheap so that covers a few tank fulls for the price of the bank 1 sensors. Swapped them a bit back but I don't drive the car any distance to get a good reading on MPG. Took the barge out for a 350 mile round trip today. The bad part was getting stuck in LA traffic for an hour doing about 2-18 MPH for 22 miles. After that and the return drive the calculated MPG is 26.9, pretty good for having 208K on it. I would love to see what a non-ethanol fuel would do. Was happy to see the car can still do pretty good on a long trip.

(Wasn't far off calculating, gas that went in was an actual 12.9 gallons dropping it a bit.)

 

Mine's been doing about 17-18mpg average in total. I do end up doing a lot of in-town driving and don't get to use the highways much, but I think the highest I've seen on a tank was 21mpg on a long highway trip where my odometer was pushing 800km by the time the light came on. I hear the Celsior got a steeper differential gearing than the LS400 so I expect my fuel usage is slightly more overall. I think it was the same ratio as what was used in the SC400.

Recently I'd seen a decrease down to 13mpg at my last trip to the gas station, so I've replaced the coolant temperature sensor in the hopes that it was the culprit. So far it seems to be doing better, doing nothing but short trips on this tank so far and half a tank was right at 250km, which lands me right at 17mpg for a tank if this trend continues. I have a long distance highway trip in the coming weeks so I'll report back once that's over with, I'm hoping for a new record.

 

1999 Lexus LS 400, 220,000 miles. Average MPG is 22, city & highway. I use 87 Octane exclusively. I tired premium, mid grade and ethanol free, no discernible change in mileage. I have checked every tank for MPG since owning the car, (over 100,000 miles ago). Keep the tire pressure at 40 psi year around. I do not use the onboard mileage indicator as it is at least 2 mpg better than actual. My odometer has been verified by GPS so it is always actual miles driven divided by gallons put in.

 

1999 UCF20 @ 200k miles, 91 octane only

• old temp sensor: 16 city, 22 freeway
• new sensor/seafoam: 20 city, 25 freeway

psi around 38

 

 

17 all city.Mid to high 20's at +/- 75 mph Highway.Those are averages,its possible to do better in ideal conditions.Amazing car.

My advice line is this....GET SERVICE RECORDS. An older car with higher miles is better than a car with lower miles that hasnt had scheduled maintenance done.Rubber wears out related to age no matter what else.

Being older classic cars now my old car advice applies,buy the best one you can afford.Let someone else bear the expenses of replacing all the wear parts.Buyer comes out way ahead.I always buy the seller,not the car.Examples...

1998 LS400-Lexus Service Managers 'lifetime' car.245,xxx miles.All expensive stuff done and up to date.Lifetime serviced by Lexus.

1967 Jeepster Commando- 100,000 miles.Veterinarian 2nd owner-Has Money.Mint vehicle

1965 Baja Bug-Good shape.I rebuilt or replaced everything but body and pan.Cheap to do,had me a new car.

1959 VW Transporter-100,000 miles.2nd owner in Berkeley Calif. Seller had Money.Mint vehicle but for battery pan rust.

 

1998 LS400
192K miles

i get about 310-340 miles to the tank. Usually fill up with about 40 miles left to go in the tank.
my commute is a mixture of stop/go and a couple of miles at 50-65 mph
my commute back and forth to work is 15 miles each way
my trip info screen will vary anywhere from 17.9 to 21 mpg
on long highway runs it can get me about 24 MPG
car has always been a commuter for me so ive never really taken it out of state on long trips

 

18 in city around 27 28 on highway. My wifes grand caravan gets 27 highway but 15 city.

 

i generally average about this from mixed highway (70 - 80 mph) and around town driving, including the occasional pull up to 5000 rpm in 3rd lol



literally just cruising along at 55 on flat level ground you'll be getting close to 35 mpg assuming everything's working correctly, but you can still get up to 30 mpg going 70 -75 (depending on the road and conditions)

 

Many factors to include which comes to how well the car has been cared for. A sample that is running well, all systems in good functioning condition and modest miles may pull similar MPG as on the window sticker. The higher the miles usually introduces wear so that can be expected to reduce those numbers. The ethanol infused gasoline will reduce that from 8-15%. The reduction in MPG is about 12% that I've calculated for ours. The choice of gasoline be that the grade and how much weight the car has added like heavy audio gear will have impact on overall MPG numbers.

Shell V-Power returns the best MPG for ours. Ours doesn't get driven much in commute traffic so on the long runs, it will do 23-24.3 MPG all highway. In town mixes can vary from 12-16 MPG. This also factors with the slightly lower diameter of the wheel tire combo so overall it is pretty close to what the window sticker would be. I don't drive it hard either.

 

99 LS400

Freeway 20mpg
city 18mpg

I do mainly freeway driving for work and usually drive between 65 and 80 mph My average being 75mph.

 

 

something's very wrong with your car if you're getting only 20 mpg highway at 75 mph, that's the mpg you should be getting at close to 100 mph lol

 

!996 ls400 249k miles

18/19 city
25/27 highway

 

Around town I see as low at 16-19, but I'm talking where I barely see above 40mph. True stop and go with zero highway travel.

Highway trips I see 25-27 depending on hills\traffic.

Looks like I'm where I should be