[dammit]

Strange thing, normally it is the other way around. But for me, I am experiencing significantly high fuel consumption when I do a lot of highway driving. I have been using Fuelly to track my usage. When driving on 110/km/hr freeways with no traffic, pure highway, I usually average 9.0L - 9.5L/100km (this is on a tank basically used solely for freeway).

Yet when I am in bumper to bumper city traffic, using a full tank I can get around 8.0-8.5L/100km. (a good 1 L less)

I noticed when driving at 110k/hr, my RPM sits at 3,000, which seems very high for 4th gear? Does everyone elses do the same?

Does anyone have any advice on what I can look at to reduce fuel consumption for the freeway driving?

I have a 2012 FD 2.0L Petrol Trophy (auto) model.

[Phil №❶]

This is unusual.

Probably need more information before any improvements can be made. A few questions first.

How many years of driving experience do you have ?
Do you travel with windows up or down ?
What type of terrain is the freeway traversing ?
A/C off or on ?
How many k's has the car traveled ?

Other petrol owner's will know whether the economy you're obtaining is considered normal or not.

The three areas of interest to me are,

- Windows should be up at high speeds to reduce drag.
- A/C off uses less fuel.
- You may have a binding brake, so next time you drive, feel each rim to see if there is a large variation in temperature. The 2 fronts will be hotter than the rears.

This is where I would start to investigate.

[Dazzler]

Hi Dammit,

 

Could your auto box be slipping or something? When you select gears (particularly reverse) is there any hesitation before engagement.

That is higher than my 3.6 Litre V6 Auto! 

[dammit]

It's funny you should mention that Dazzler. I noticed last weekend when I was driving particularly when I was in drive then quickly came to a stop and tried to slot into reverse, that I would have trouble getting the stick to go to that position. (eg when doing 3 point turn or reverse parallel park). When driving at 110km/hr at 3000rpm, it definitely goes into 4th gear, because if I drop the gear lever back from Drive to 3rd, the revs do go up and I can hear it change down.

Does it seem like there is a problem with the auto transmission?

To answer your questions Phil-
I have been driving for ~12 years now.
All windows are always up.
Terrain is mostly flat, this example fuel consumption was on the Hume Highway out of Sydney. There are the odd hills and steep gradients but very rare.
I do generally always have a/c running, either on fan speed #1 or #2.
I have been filling up with Unleaded 91 which generally these days is the ethanol blend. I have actually achieved better fuel consumption off this than the proper Unleaded 95 which surprising.

Re the possible binding brake - sorry for the newbie question but would my brake lights stay on if that happens? To check the temp do I just feel the metal mag wheel on the rims to see if one is scorching hot, or are you saying touch the actual disc or whatever for the brake inside the wheel?

I purchased this car back in August (2nd hand). It had 30,000km and had just had it's 2nd full service.

I guess this type of fuel economy might not be that excessive for the car and compared to others, but the thing concerning me is the fact that city driving should always be drinking more fuel than highway/country, yet in my case it is the other way around which makes me wonder if something is wrong.

[Phil №❶]

Thanks for the replies to my questions 


No, your brake lights will not be on if a brake is binding, it means that the brake pads are (for some reason), unable to completely let go of the brake disc. This would cause friction and increase fuel consumption. To check temps, just touch your wheel at the centre with the back of your hand, no need for any tools or to undo anything. They should be slightly warm, but not excessively so. 75% of braking is done at the front and there is transmission of engine heat as well so expect them to be warmer than the rears. The main thing is that they should be at the SAME temp, (Front compared to Front, Rear to Rear).

The only other thing that is different freeway to city is wind resistance, but there is little you can do to change that. It is higher @ 110 than @ 90 kmh but you would be holding up traffic to travel at that speed and creating a traffic hazard.

It could simply be, that the 2.0lt engine consumes this amount of fuel, at that speed.

A/C take about 5hp from the engine to drive the compressor, it is more noticeable in a petrol engine than the diesel. You might try doing without for a while and see if that is a contributor. If so, you'll have to decide whether to be comfortable or have better economy. I remember form my dark Ford XW days the service manual stated that in hot conditions, the compressor provides 4 tons of compression per MINUTE    That's a lot of energy.

[Just Rick]

dammit,I don't have an auto nor a petrol,but I do have two deisels both Manuals,I have noticed that I use far less fuel in the mtro area than on the highway,If I travel at 110kph,just by slowing to 95 to 100kph I can drop the fuel consumption by up to 1.5l/100.

even more interestingly is even after driving slower to drop my fuel use at highway speeds,in one of our cars I have noticed,the trip computer tells me I am using 4.9l/100 hwy speeds,then drops to as low as 3.8l/100 in the metro area(not peak out traffic)which surprised me,I was always of the opinion that you should get better milage on a lomg run,not stop start around the metro area.

Like Phil said many questions to answer as to what can affect your economy,drop your highway speed by ten or fifteen,we're a long time dead,no need to rush to get there any earlier.

[Phil №❶]

 

I notice a similar thing in ours too, Rick-p.

Forced to travel in Adelaide @ 50kmh + traffic lights, so fuel dropped to 4.9 from 5.2. Now, I smile in city traffic. 

This was immediately after a fill, so there were no prior kms to affect the computation.

Just love this little Diesel.

[dammit]

I touched all four wheels after a 110km/hr 50km trip, and they all seem relatively the same heat wise. Front ones after about 3 seconds holding my hand on them it is too hot to touch (e.g. 80 degrees?) and back ones after about 5-7 seconds getting a bit hot to touch. So not sure if that seems too hot or because they seemed comparable it rules that out? (it was a really hot day in sydney today so I expect driving along in a 30 degree day would add to the head to the rims being in the sun too).

A/c - well I def can't drive with the a/c off...lol. I have 2 ilttle babies too and we all feel the heat 

I noticed too if I slow to 100km/hr, the RPM drops to 2,500. If I am 110-115km/hr it is at the 3,000 mark. I don't know if this RPM is a correlation to higher fuel consumption or not?

I know I could always slow down, but I sometimes have to drive long distances and am very time poor so want to at least be able to do the speed limit. Might just be that this vehicle is more tuned for city conditions so the gear ratios have been set with city driving in mind at the detriment to freeway driving, what do you all think?

Or do you think this is something I need to go back to the dealer and/or repair place to investigate?

[Dazzler]

@ Dammit,

The 4 speed Auto has had some issues but not usually until the kilometres get up a bit. Also the Diesel Auto seems slightly more prone to issues due (I assume) to the extra torque of the motor)

Symptoms are slow to engage reverse (mainly) or drive .. I haven't had an auto so not sure what else.

The new 6 speed Hyundai Autos are a bit more efficient but the 4 speed in the FD model was quite inefficient adding about 1.5 L/100 kms to the Diesel and possibly more to the Petrol models.     

Hopefully the first owner was a private owner and had the book stamped so you get your full 5 year warranty (just in case)  But you should be fine.. 

Further to your latest post, sound like just business as usual. Don't think there is much the dealer can do.

[neptune]

The new 6 speed Hyundai Autos are a bit more efficient but the 4 speed in the FD model was quite inefficient adding about 1.5 L/100 kms to the Diesel and possibly more to the Petrol models.   

with the petrol models, I have had both in autos and I get better fuel economy with the four speed auto than the GD 6 speed auto box. This has always been my main bitch with the new model....I get two extra gears and get less fuel economy than a four speeder....ugggg!!!!!
Also the faster you go, the worst the drag is, and hence the fuel economy is not there....the optimum speed for the petrol autos seems to be around 90kph 

[diablo]

Also the faster you go, the worst the drag is, and hence the fuel economy is not there....the optimum speed for the petrol autos seems to be around 90kph

I find that 60mph gets best fuel economy in my 1.4 petrol. 70 and above it drops to and below fuel usage around town.

It is the worst car I've ever had in that respect. I'd assumed that the drag coefficient in modern cars was always improving.

My 2 litre Laguna was only sipping petrol at 70-odd mph.

I suppose that the 1000 rpm per 20mph ratio in fifth gear doesn't help much either.

[Phil №❶]

Those wheel temps sound a bit high. Could you try doing the same thing on a cool day and after about only 20 kms. If there is a brake issue, the wheels will already be quite hot, normally they should only be comfortably warm and the rears, quite cool. Try not to brake heavily during the test.

[Asterix]

If you can't touch the rear wheels there's something wrong, and most likely as allready mentioned, the brakes are sticking.

If you can lift the rear wheels off the ground the wheels should spin freely without any problems.

[Lakes]

Would depend where you where driving at 110kph, like sydney Newcastle F3 , or Hume hwy toward Canberra both directions at that speed would not expect good economy as lot of climbing. Plus you said you like to rush.
My father 94 he has a new Elantra auto 1.8 petrol never turns the L/100k off & sounds like he drives like you always has his trip PC showing L/100k of 10L/100K
But he loves his car & not too worried about fuel economy only does low k's. Just thought I would mention . Only way to get good economy is drive slower on open road, & in the city don't excellerate or brake hard or tail gate. Drive smoothly plan ahead so you can brake gently

[Tourer_Guy]

Check your tyre pressures also.  Over time, the pressures drop.  You should have at least 30psi (preferably more for best fuel consumption) in each.  Don't overinflate, though.  I run mine at 36psi.

[FatBoy]

As others have said, reducing your speed will reduce your drag.  It is not a linear relationship, as drag increases with the square of the speed. 

Drag = (Coefficient of Drag) x 1/2(Air Density) x (Speed) x (Speed)

As the Coefficient of Drag and Air Density are things you can't control (and they don't change), you can remove these from the simple equation to the following.

Drag = Speed x Speed

Therefore if you increase speed by 2, then you increase the drag by 4.  Increase it by 4 and you increase drag by 16.

I used to be able to achieve 5.3 l/100 km around hilly Tassie, and I would do the speed limit.  I could reduce the consumption to around 4.5 if I slowed down, BUT I wanted to get to the destination without spending needless hours on the road.  What I'm basically saying is that if time is valuable (more valuable than the extra fuel consumption) then don't change your habits.

[Shambles]

[The Gonz]

  Keep up, Steve!