2006 Sonata GL MPG

I getting MPG gains as the weather warms as well-haven't hit 30 yet though.

What engine/transmission combination do you have?

Matt

v6 auto (LX)

Hitting 30 consistently with your LX would be very impressive as, if I recall correctly, that is the EPA highway rating. You wouldn't expect that unless you were on a long trip. If you are even getting close to

30 in daily driving, I'd say you are doing well.

Matt

I think I know why my mileage took such a step change from 27 to 31 in the last two tankfuls. I was thinking it must just be the warmer weather and the car getting broken in more, but I no longer think that is the case.

A friend at work was telling me that his Civic HX (I think I got that right) gets 46 MPG during the summer, but only 40-42 during the winter. He said it changes when they switch the gasoline from summer blend to winter blend. I hadn't even thought about that, but I'm betting that is what also affected my Sonata.

Have others who live in northern climes that use different fuel for winter vs. summer seen this same behavior? My minivans don't seem to be affected as dramatically, nor my pickup. That would certainly explain the rapid change. I was trying to figure out how a slow warm-up in the spring could have such a rapid change on the mileage. It didn't make any sense, but changing fuel blend does make sense.

Matt

My last tankful achieved 31.6 (nearly 500 miles on one tank!) so things are still improving slowly. Hey, this car may bet 34 MPG before the summer is over!

Anyone run theirs dry yet to see if the tank capacity is really as advertised? I haven't run more than about 15 miles after the light came on, but have yet to put in more than 15.6 gallons, which means I should still have a couple left.

Matt

I haven't run mine dry, but I've wondered the same. The most I've ever put in is 15.6 gallons as well and it's usually closer to 15. I've got the GLS with the trip computer and the light usually comes on with somewhere between 45-60 miles to go on the Range. Based on the 27.5 MPG that I've been averaging, that's another 1.5 - 2 gallons or so...assuming the computer is accurate.

Doing some rough math, that seems to be a little less than the 18 gal. capacity. I'd prefer not to find out the exact amount the hard way, though. :-)

Barry

In the past, I've run some vehicles dry on purpose (with a can of gas along) and one by accident. The latter my current Chevy truck which I've twice confirmed holds about two gallons less than the amount stated in the manual. The first time it ran dry, I was literally able to coast into a gas station ... talk about dumb luck. I was only able to put in something like 24 gallons, and I believe the book capacity is 26 (I haven't checked in a while so this is purely memory). In any event, it took two gallons less than specified. So, I carried gas along next time, which was easy as I had a 50 gallon tank and pump I used to refuel my airplane and ran it dry on purpose. Same result, it took two full gallons less than advertised. This is good information to know in a pinch. Also, the truck has a very nonlinear fuel gage. It takes about

90 miles to get the needle down to the full mark after a fill-up. The needle goes about a quarter tank above the full mark when full. It then takes about 180 miles to get to the half-tank mark. And then about 130 more and you are out. Once below the quarter tank mark, the gauge drops like a rock.

Matt

Running an electric fuel pump dry is really hard on it. Even sitting still with not alot of gas in the tank is a bad thing to do. They are cooled by the gasoline. While the car is in motion, whatever gas is left in the tank is sloshed over the pump and helps cool it. While running the car out of gas once is not likely to kill the pump, it really doesn't help with it's longivity.

I've heard both sides of this and am pretty sure this is another urban legend. A fuel pump designer in another ng (I believe the Chrysler group) said that the fuel pump is cooled by the fuel going THROUGH it, not sloshing around. If the fuel pump is still pumping fuel, then there is no danger of overheating it. And once the tank runs dry, most folks turn off the key before the fuel pump runs long enough to damage the pump. Personally, I don't know for sure, but I've run my cars nearly to empty for 20 years and have had only one fuel pump failure and that was after 150,000 miles, which is considered to be decent life for an in tank fuel pump.

Matt

Call it urban legend or whatever you want.

I knew of a guy that owned a garage in Rapid City, SD. Every Summer, he made sure that he had access to fuel pumps 24-7, because people were always coming in off the mountains, stopping for gas or whatever in Rapid City, then be unable to start their cars again, because of fuel pump failure.

In almost every case, there was mountain driving in the heat of Summer, and the consumers confessed to usually driving their fuel tanks down "further than they should have more than they should have."

Bottom line - since it is at least possible that this happens, and since it makes little sense to run your fuel down that far anyway, just don't do it. Fuel pumps are an expensive job, unless you are one of the lucky ones that has an access port to it in a trunk or a back seat - otherwise, it is drain and drop the fuel tank and go from there.

Tom Wenndt

That's an even better legend! We're supposed to believe that all of the fuel pumps magically failed in Rapid City only when they stopped for gas? They didn't fail 10 miles before the City or 10 miles after? I guess the question I have is what were the gas station folks doing to kill the fuel pumps so that this garage could fix them and how much of a kickback was he giving to the gas stations. They had scams like this a few years ago on 20/20 or one of those similar shows.

Sorry, but I'll believe a fuel pump designer before I'll believe a mythical garage owner in Rapid City, but that's just me...

Show me one warning in an owner's manual or shop manual about not running your tank low to prevent fuel pump failure. Just one...

It's possible that the sun won't come up tomorrow also, but I don't worry too much about that. :-) There are enough probable things to worry about that I don't need to worry about the improbable ones.

I don't see why it makes sense to stop and waste time buying gas more often than one needs to. Once I know that I need gas, I stop and fuel up, but I don't see any reason to stop every half tank when I can run down until the light comes on or nearly so and have 100% assurance of getting to the station, since I know where all of them are on my daily commute. I agree that if you are traveling and not sure where the next station is, then stopping the 1/4 tank point or so makes a lot of sense.

Matt

Hyundaitech,

What is your take on this? Do they warn you about this at Hyundai tech school? Do you see frequent fuel pump failures on Hyundais that might be attributable to running low on fuel often?

Matt

I think I would have to call that urban legend Tom. Either that or bad data. It's just wildly inconsistent with the experiences of literally tens of thousands of vehicles driven in virtually the same conditions every day. I suspect the fellow you know of was overstating a case.

I'm talking from experience on Chevy 3500 Vans. I worked for an electric utility, and many of the vans idled for hours to provide AC power for certain test equipment. We had a rash of fuel pump failures - mine included. We were cautioned not to idle them if the tank was less than 1/4 full because that would leave the motor of the fuel pump out of fuel - the intake was still well under the fuel level. I know my Town and Country passes fuel over the motor when it's pumping -

- so what was said about the fuel pump designer is definitely true about Chrysler. The Chevy pump motor is out in the "open" in the tank. It is only cooled by fuel around the outside of it. I don't know if that's the case with the Hyundai pump. There's also baffles in the Chevy tank that help with the level. From what I saw, driving the vehicle with a low tank didn't seem to kill them. It was when the vehicle sat still even when the tank wasn't terribly low. It's not entirely urban legend.

Also, once an engine stalls due to lack of fuel the pump shuts off after a few seconds. It's not controlled by a pressure sensor. It's controlled by pulses from the ignition system. Cranking the engine starts the pump for a few seconds, and it stops a few seconds after you let go of the key. You'll not likely cook a pump in the short term - especially with no back pressure.