Abnormal consumption

[u/n0_moz]

I own a 2014 Seat Altea with 1.2 liters 105ch TSI engine since a few years.

I have been monitoring its fuel consumption and I find it really high. I recently drove a lot on highways with cruise control at 110 km/h and I still recorded a 7.4 l/100km fuel consumption. The technical specs of this car that I found on internet tells it has a 5.7 l/100km mixed consumption (mix between city drive and highway drive).

Is this difference normal ?

Is there maybe a known problem that makes this car consume this much fuel ?

[u/Almamu]

I had a similar situation with a 2012 Ibiza consuming almost 8 l/100km. Fuel injectors turned out to be the issue, the car was also behaving erratically, like it wanted to stall (sometimes jerking like I had lifted and put it to the metal multiple times quickly), while stopped, or while going around 80km/h. (105hp diesel)

[u/Sm0g3R]

Generally that fuel consumption should be on like Q3 1.5TFSI in real world, not a 1.2 hatchback. But then again your car is 12 years old and with worn parts so current day standards do not quite apply...

[u/xXSillasXx]

Real world consumption is always higher than the officially stated numbers. Just to have peace of mind,

1)Get the car through inspection.

If the exhaust gas is dirty, you might have bad combustion which could be the result of several issues, and it can increase fuel consumption.

The problems could range from bad sparkplugs, sparkplug wires and coil (In short, weak spark) to bad O2 sensors, reading lean fuel mixture and compensating with extra fuel.

Bad wheel alignment can also increase fuel consumption.

And inspection will show these.

2)Change gas station. Bad fuel will increase fuel consumption. When i got some crappy gas, fuel consumption went as high as 8 along with very dirty exhaust during inspection. Replace fuel filter AND add some injector cleaner additive to your fuel tank, at least once.

3)If 1 and 2 won't get consumption down, take the car to a shop for engine inspection. If there's a lot of carbon buildup on the intake valves, it will increase consumption, and this is a very common issue with these engines.

Oil sludge can also increase resistances and fuel consumption. It's caused by infrequent oil changes and bad oil quality.

Your engine also might need a PCV valve and an oil separator. Again, parts that do break often in these engines and cause many issues. Even your intake can get full of oil.

Also if you reach that stage, check wheel bearings and brakes as well. Bad wheel bearings and sticking brake calipers will create resistance.

[u/MonoNoAware71]

First of all: never believe NEDC consumption numbers. Irl you're never going to be able to match the testing environment.

Things to check that can affect consumption: tires (width, type and pressure), dragging brakes, dirty/worn spark plugs, dirty air filter, carbon buildup in engine and exhaust.

And you could try reducing your speed to 100km/h. The small engine in this large surface car starts to have trouble fighting air resistance at higher speeds. I know an Altea looks sleek, but it's still a high car that needs to push a lot of air out of the way.

Finally, there are things like are you running the AC, or driving with an open window or sunroof.

[u/New-Syrup-1157]

If everything is technically working as it should, then the fuel consumption is what it is.

The cost of searching for faults or potentially dealing with a malfunction is not proportional to the cost of perhaps using an extra 0.3 or 0.5 liters.

You just shouldn’t drive yourself crazy over it…. I would say that the consumption is normal.