4 cyc vs 8 cyc mpg

[saltysteve]

I recently have been looking for a lgt- sadly ive discovered it gets about the same gas mileage as my lincoln ls V8! the lgt only gets 2mpg better.

WOW! this car is really bad on gas

[saltysteve]

is that b/c of the awd?

[Brady]

Well, it is somewhat because of the AWD, but that's only one factor. The AWD system certainly introduces more driveline drag which does punish fuel efficiency. But part of it also is the fact that the LGT has a turbo and puts out as much power as the LS V8. The only real way to make horsepower is to burn gas - so if they both have the ability to burn the same amount of gas and make the same power, it stands to reason that given similar weight, they should get similar gas mileage.

 

Half as many cylinders does not equal half as much gas consumption.

[gianspi]

I get 22mpg mixed city and highway driving fairly aggressive. If you obey the speed limit and accelerate slowly you can get 26-28mpg highway. Extremely aggressive driving will net you single digits.

 

It's all on the driver, not the car.

[Brady]

That's also true ... I once got over 480 miles on one tank - easy highway driving the whole way and yielded just over 30 miles per gallon. Either way, our engines are not engineered for fuel efficiency - if you want that, you need to trade performance.

[DKB_SATX]

TANSTAAFL. You make the power, you burn the fuel. You asked in another thread about mods, so you may be interested to know that many people who've installed the Accessport engine-management upgrades report slightly better fuel mileage when they're not using all that extra power.

 

I regularly see 26 mpg or so on highway trips, 22 or so around town (light traffic.) That's with a manual transmission and an '05 GT Wagon. I could get better mileage with a Prius, but I'd be bored.

[saltysteve]

makes sense.

[Riggs]

AWD costs you somewhat.

[NSFW]

Fuel economy depends on many things, but the number of cylinders is not one of those things. Displacement is a big factor though, and so is gearing.

 

I'm going to guess the V-8 in your Lincoln displaces a lot more than 2.5 liters. And I'm going to guess that when you're cruising down the highway at 60ish, your Lincoln revs lower than your Subaru. And in terms of fuel efficiency, those two things almost balance out, with the Lincoln only being a couple MPG worse than the Subaru.

 

Am I right?

[NSFW]

And did anyone else click this thread because they wanted to know how an 8-cycle motor works?

[Brady]

 

It did cross my mind.

[lawl]

if i can outdrag v8s im not complaining if my mileage is close to theirs.

[ehsnils]

Well, it is somewhat because of the AWD, but that's only one factor. The AWD system certainly introduces more driveline drag which does punish fuel efficiency.

 

And if you do compare a NA Subaru with just about any other car of similar size and weight you will find that they are very similar in fuel consumption which means that the drag imposed by the AWD is negligible. And don't forget that the advantage of AWD will also provide you with less wear on the tires. (track driving excepted).

 

The problem Subaru has is that all the turbo engines are thirsty beasts. They do have power to compensate with though...

 

As for engines with more cylinders they do suffer some extra internal drag due to more mechanical parts (camshaft lifters, spring compression, extra mass (piston/conrod) etc. However the equation isn't simple since a V8 usually works at lower RPM:s than a 4 cylinder, which means that the moving mass factor difference may be small. But don't forget that a V8 also contains more number of parts which means that if the components and designs are equal in quality the larger number of components will statistically make the V8 more prone to break down. (I know lies, damned lies and statistics... )

 

It is also a question about how you actually drive your car. If you want power and get a good power to weight ratio a turbo engine is a good choice but if you instead drive on torque a NA, supercharged or (turbo)diesel engine is better. Today you can hardly find a NA diesel engine anymore - at least not in cars, and only occasionally in trucks.

[NSFW]

The problem Subaru has is that all the turbo engines are thirsty beasts.

 

Yes, and in more general terms:

 

The problem we all have is that creating more power requires burning more fuel.

[Hugo L.]

I'm dying to see how mine will do (awaiting delivery on an '05 stage 2 Legacy GT Wagon 5MT).

 

My E36 M3, even it's a heavy 'vert, is very frugal on the highway (I managed 30 mpg driving 70 mph).

 

Of course, my Subaru will mainly replace my gas-huzzling 4Runner, so I'm bound to see an improvement anyway.