17/23 fuel economy for auto lgt 2008?

Folks with LGT autos, is your mileage really that bad on the highway? I don't think it is... EPA is redoing their fuel economy measurements for 2008, and here is the estimated change according to kiplinger (http://kiplinger.com/tools/gas_mileage/). Methinks they jumped the gun on this one:

Subaru Legacy AWD 2.5 Automatic
2007=19/25
2008=17/23

That figure for 2008 seems about right for my 07 OBXT.

Can someone shed some lights here why 2.5 turbo gets such a low mileage in both local and highway?

It's pretty bad for 250HP&TQ level engine in compared to new G35 and 335i. There are couple of things that I wish Subaru to consider oadding on future models is "6-speed auto" and "direct injection technology" to improve engine response, performance and efficiency.

Cheers

Turbo design is restricting exhaust flow, in boost or not. That is part of the reason.

> Methinks they jumped the gun on this one:

I have NEVER managed 17 in the city. 23 on the highway on the highway seems about right, though. I can do better with the cruise locked at 55, but what's the fun in the that?

-
Jim

Right at 60 I would be better. But at just doing the speed limit here at 75mph I get around 23.

Originally Posted by Suby4me

Can someone shed some lights here why 2.5 turbo gets such a low mileage in both local and highway?

It's pretty bad for 250HP&TQ level engine in compared to new G35 and 335i. There are couple of things that I wish Subaru to consider oadding on future models is "6-speed auto" and "direct injection technology" to improve engine response, performance and efficiency.

Cheers

Apparently direct injection isn't fast enough for high RPMs and so it is less than ideal for a turbo charged car. People suspect this is why the MazdaSpeed 6 falls flat up top.

The AWD robs some mileage too, but I'm not complaining. In fact I think the conservative tune Subaru gives the LGT may contribute to the infamous stutter. Cobb's Stage 1 map killed a couple MPG, but also killed my stutter.

ECU management FTW.

23mpg is about right for my car. It is a fuel swilling engine, especially considering it's modest power output.

Sounds right to me for my MT.

<--foot may be a little heavy

for my 05 auto that 07 figure seems right on...

I am a extremly heavy footed driver and I still seem to get around 18 on the streets and about 23 on the highway. MT

Direct injection is fine for high RPM, as least according to my limited grasp on the subject. MS6 and MS3 problem is more turbo size-related up top than anything I would suspect. Look what happens with the 2.5L WRX and FXT for example.

Closest I can think of on the market is VW's lowly 2.0T workhorse motor that revs to 6700RPM and has a turbo and direct injection. Low-revs and direct injection can work as well. The GM turbo 2.0L puts out more HP and torque than the LGT does with 0.5L less displacement and a redline of 6400RPM.

Peak HP and TQ numbers for the most part are the effect of turbo size not direct injection. Substaining high rpm power on a turbocharged vehicle maybe a problem having to do with direct injection.

ok, some things:

mazdaspeed 3/6/mazda CX7 use a very poorly thought out intercooler design, with ductwork that is wholly insufficient at cooling the intercooler.

the vw 2.0T is choked by a very small compressor, which is why it makes peak torque at 1800rpms; its all downhill from there.

the LNF in the solstice GXP is an amazing piece of engineering.
not only does it make more power and torque from less displacement, it does it with less lag then my stage2 legacy!

There are NA direct injection engines that redline over 8K; I really don't think it is an engineering issue in terms of being able to deliver large amounts of fuel at high RPM with direct injection.