turbo VS non Turbo fuel consumption

[GTB-R]

Here is the :

2009 Subaru Liberty GT SpecB R 4GEN

Fuel consumption :
Fuel Urban (l/100km) 14.6
Fuel Extra Urban (l/100km) 8.1
Fuel Combined (l/100km) 10.5
Weight :
1545kg

Here is the :

2009 Subaru Liberty Heritage 4GEN

Fuel Urban (l/100km) 12.4
Fuel Extra Urban (l/100km) 7.1
Fuel Combined (l/100km) 9.0
Weight :
1365kg

I'm curious how more fuel efficient the non turbo 2.5 litre here is in comparison to the turbo version. I had assumed that when the turbo is not running that it (mostly) bypasses the turbo itself & heads out the exhaust. I can't compare apples with apples here clearly for many reasons; one being there is a 180kg difference in weight, two different transmissions though I don't know the ratio of the 5 speed box in the Heritage, compression is also different but don't know if that impacts on fuel economy.

So the question is, can a turbo car be as fuel efficient as a non turbo car if everything else was the same?

[GTB-R]

also thought I'd throw up a photo of my current weekly fuel consumption & consumption since the purchase of the car. Consumption since purchase also includes 4 car club runs through the Healseville & surrounding areas.

The other is my figure after only some short highway driving from my father’s place in Doveton back to my place in town. Clearly the overall has come down too.

http://imgur.com/lovjC.jpg

http://imgur.com/nvHxt.jpg

[lammi]

oh wow.. call me a noob, but what headunit screen is that with all that info!?

[GTB-R]

It's just the SatNav console in an 09 GTB-R

[Lukovitch]

Fuel consumption in a GT......

[GTB-R]

Isn’t a turbo a way of getting power when you need it & fuel economy when I don't?

[coyote]

Isn’t a turbo a way of getting power when you need it & fuel economy when I don't?

No, that's what your right foot is for.

[ROB-80E]

Turbo engines will always have lower compression. This stops head gaskets blowing and less stress on pistons, rods, bearings etc etc when on boost. Lower compression has it's downside though, that is less power, but that's why they throw on a turbo.

For day to day driving, you'll never get close to the same fuel efficiency as an n/a engine. Reason being, it is hard to get the car to do anything when not on boost (for reason above), and the turbos are designed so efficiently that they produce positive pressure early in the rev range.

I've just swapped to an auto GT from a manual 2.5i (both MY07's) and so far the GT is about .6-1.2L/100km more thirsty. But as other guys have suggested, you don't buy a turbo car to be worried about fuel economy.

[GTB-R]

Thanks for the figures, they do offer some insight.

I think it's about economy & handling, if a V12 over the front wheels carried no weight nor economy disadvantage surely we'd all be happy with constant power all the way through the rev range.

As it doesn't we utilise superchargers, turbo chargers & small engines to offer economy of fuel & of weight to support handling characteristics.

[Roddez]

Don't forget that there is a horsepower difference between the two engines.

In order to produce more energy from an engine, you need to put more energy in.