ThePablo

Hope this isn't redundant, I've read a few other posts along the same lines here, but wanted to know if I should be bring my situation up with Lexus.

Just purchased my '13 RX 350 F Sport last month, have put about 2K miles thus far. A great majority of these miles are highway, so we're getting 21 mpg. Ever since our first tank, I've noticed some inaccuracies, at least in my head they are. I'm use to buying gas when I hit the last notch on the fuel gauge, depending on how much of a hurry I'm in, I can take it beyond. The first tank I took it right to the end and filled up with 16.23 gallons. The next time I took it a little farther, filled up 16.15 gallons. Then I decided to watch the Cruising Range and see if that aligns with the gauge going empty. Mine doesn't. I usually hit 0 miles left a little before I hit the last notch. So I told myself to push it a little further, and entirely past the last notch, and aligned with the E, which was probably close to 50 miles from the time I hit 0 cruising range. That fill up was only 16.63 gallons to fill up.

I guess my question is, is it normal to have 3 gallons left in the tank when hitting E? Is the cruising range worth reading? Should I try and get my RX that low to where I'm filling up 18+ gallons per fill? I guess its that much less I have to fill up, but really the price doesn't matter to me, I just want to make sure I'm utilizing my fuel efficiency. I'm also trying to build up my highway MPG, as our latest trip down to LA only provided us with 22.2 MPG, which is along the 21 MPG on the invoice for combined.

Anyways, thanks in advance, is our first Lexus, so wanting to make sure we're treating it right! What does everyone else use in regards to gas type, we've been using mid grade as our sales guy suggested it, even though 350 only require unleaded.

UCSB

Your fuel gauge is working correctly. Lexus leaves you a reserve in your tank at empty. There was a thread a while back where people discussed this topic in detail.

On the mileage, it sounds like you are getting about what is expected. Freeway speed is the major factor in gas mileage. I took a trip last Thursday and was keeping my speed down in the 60 to 65 or so range and averaged 33 MPG on one direction, when I came back I was driving faster and was averaging closer to 30 MPG. Your mileage might improve as your engine get more miles on it.

ecr72

How is fuel efficiency related to the accuracy of the gauge and cruising range? I'm not following.

As for gas, I'd use what the manufacturer recommends, not what some sales guy suggested. Mid-grade gas is a gimmick. I'm not aware of any manufacturer who recommends mid-grade for any of their vehicles. It doesn't make sense to be concerned about fuel efficiency and then turn around and put in mid-grade gas when it calls for regular.

User 41924

Back in the old days, I was taught to buy fuel before the tank got too low. Especially with fuel injection. The reasoning was that you would pick up more sediment from the tank, and risk clogging injectors or carburetor jets. Does this still (or did it ever) apply?

GrandSedanFan

iTrader: (1)

Fuel efficiency is tied directly to the Cruising Range. The computer reads the fuel level and then uses the average mpg from your last fillup to calculate Cruising Range. Sometimes I get 300 miles to empty on a full tank, some times I get 260. Depends on how much city driving I had done on the previous tank.

Yes, but now because fuel pumps are mounted in tank and cooled by the gas around them. Don't run your car down to E too often. Sediment is also an issue, but most people don't keep vehicles long enough to need a new fuel filter.

You're not treating it right. See above. Don't run your tank down to empty. The reserve gas is there for emergencies and to keep your fuel pump cool. This nonsense about the fuel gauge and miles to empty has nothing to do with the actual fuel economy you're getting. Your truck has a few thousand more miles before you're going to see your best fuel economy. Fuel economy is based mostly on how you drive. If you keep your speed steady right at the speed limit you'll do fine. Also, your average MPG calculates time at speed as well as time stopped. Even if you were doing 30mpg the entire time you were on the highway, you still won't get 30mpg average on the driver information center.

ThePablo

Thanks all, some very good tips, and I believe will put me at ease going forward.

I had my 1,000 mile complimentary service this past Friday (2/22), and let the service agent know that I felt my gauge and tank were off a bit, but they checked it and said all is well. What I didn't like is he insisted immediately when the light comes on, I have 2 gallons on reserve. But when you fill up because of only 2 gallons left, I only fill up my 19.2 tank to about 15.5-16 gallons. Will keep an eye on that, but overall will not drive to the very end, and fill when necessary.

dctex99

I must repeat...DON'T run your tanks to empty; especially in the summer, especially in hot areas like Las Vegas.....Ask a mechanic in Vegas how many fuel pumps they replace; the Taxi and limo companies don't have that problem; they fill up everytime they can..............It is the ONLY cooling a fuel pump gets.......................