4-cyl engines with MPG of 6s, and 6s of 8

[GearheadTool]

Would like to make a post regarding the way certain powerful 4-cylinder engines have gas mileage more like that of a V-6 and likewise 6-cyl, not necessarily a V, sometimes have MPG of a V-8. It seems that when 4-cyl and 6-cyl get very very powerful, OR are weak and worked hard even in a vehicle that is not performance, that the MPGs go down. So, when a 4 gets a Turbo does it diminish further?

I always wonder when I see a 6 that is rated for oh, say, 25MPG average and a four that is rated for 26-28, or gets that in service. Of course those are completely random numbers. Is there any logic to MPG ratings on different size, induction, load, and transmissioned engines?

 

[GumbyJarvis]

Weight is a factor too, Mums Equinox is a 4CYL, the 2006 Malibu she traded in for the car was a V6, According to her, she has the same Gas Mileage as the Malibu in the Equinox, 26avg

 

[JT1]

Fuel economy is more affected by how much weight, rolling resistance(wheels drivetrain), and aerodynamics of the vehicle than how many cylinders or the engine displacdment.

Also a large engine in a small light vehicle that doesnt have to work so hard to reach.and maintain speed will usually get better than a small overworked engine in a heavy car.

My 4.0 jeep gets 16mpg, mostly because its as aerodynamic as a barn door.

 

[GearheadTool]

Originally Posted By: GumbyJarvis
Weight is a factor too, Mums Equinox is a 4CYL, the 2006 Malibu she traded in for the car was a V6, According to her, she has the same Gas Mileage as the Malibu in the Equinox, 26avg


Yes. This is more what I was getting at. It seems that, on Turbo and powerful 4-cyls and etc etc, the mileage is no better (and could be worse) than 6-cyl. And I know there are a lot of different factors.. I am thinking of instances like Dodge Ram Dakota or Dodge Ram, where the Hemi gets 17MPH (?,) the V6 gets 19 or 20MPG (?) and if there was a 4cyl model (?) it gets 21MPG. ? - And similar. Turbo 4 Audis vs their 6-cyl equivalents, etc etc...

 

[GumbyJarvis]

Its all about weight distribution and aerodynamic designs, there has been many a car (Toyota & Honda come to mind) that the same car, same engine, 2 years apart, and the newer one gets more MPG, newer one has more plastic in places that the older one didnt, etc etc.

Kinda sad, Id rather be safe in a metal vehicle and lose a few MPG's versus being in a plastic contraption, MPG's dont matter when you get run over in a lego car.

 

[dparm]

The Audi 4.2L V8 (FSI & non-FSI variants) had the gas mileage of a V10: about 12 city, about 18 highway. I remember this because when I looked at buying an E60 M5 it had the exact same gas mileage as the S4 it would have replaced.

 

[d00df00d]

Originally Posted By: GumbyJarvis
Id rather be safe in a metal vehicle and lose a few MPG's versus being in a plastic contraption, MPG's dont matter when you get run over in a lego car.

Modern cars have front and rear ends that do tend to disintegrate in collisions, but that's to absorb impact energy. The passenger compartments are stronger than ever.

 

[Quattro Pete]

The V6 in our C300 has the mpg of a V8. It averages about 21 in mixed driving. AWD is probably to blame for some of it though.

 

[rationull]

With some of the turbo 4s, I've gotta think that this also has something to do w/ the richness of tune required in order to keep the engine safe from detonation at high temperatures and boost.

 

[dparm]

Originally Posted By: d00df00d
Originally Posted By: GumbyJarvis
Id rather be safe in a metal vehicle and lose a few MPG's versus being in a plastic contraption, MPG's dont matter when you get run over in a lego car.

Modern cars have front and rear ends that do tend to disintegrate in collisions, but that's to absorb impact energy. The passenger compartments are stronger than ever.


Yep, but momentum can still propel a car across the highway or intersection into oncoming traffic or whatever.

 

[71Chevyguy]

I have a Kia Optima 2.4 non turbo GDI. Fuel economy? Not so good. Sticker claims 35 highway and I have yet to squeeze out more than 24 in any driving. The driving here is very easy on the car and being a 4 cylinder I would think it could do better. Dealer swears it is fine and has no issues with it. I will say it is a nice car and is able to pull pretty hard if I ask it to but I never would have purchased it if I knew it would be this bad on gas. Just as a comparison and to show how easy the driving is here I also have a Firebird 3800 that I easily average 30MPG with and a Saturn Ion that usually gets right under 40 MPG around here. No reason for the Kia to get 23-24. I think the newer cars are strictly being programmed for emissions with no regard to fuel economy at all. I will say the Kia Optima is much nicer than I ever would have thought.

 

[Newreet]

We had a 2003 Saturn L200 automatic with the 4-cylinder Ecotec engine and the best it could average per tank was about 29 MPG. That was with Mobil-1 5W30, K&N air filter, driving at 55 MPH with the cruise control whenever possible, minimal use of the AC, windows closed, and tires properly inflated. Most fill-ups averaged around 27 MPG.

Meanwhile I knew others driving late Saturn L300 automatics with the V6 engine were getting about 27 MPG on a consistent basis too.

So we chose the smaller engine, and compared to the V6 version of that car we had worse acceleration and the same average fuel economy - rather than worse acceleration and better average fuel economy.

Needless to say we don't have that car anymore, and this was one of maybe 20 reasons why. Way to go, GM!

 

[JTK]

The 2.5L 4cyl in my 1997 Jeep Wrangler TJ drank gas like a 6cyl, but I certainly wouldn't call it powerful.

The 4.2L inline-6 in my 2005 Chevy trailblazer had V8 fuel economy. It had decent power, but certainly not V8-ish.

Joel

 

[71Chevyguy]

Originally Posted By: Newreet
We had a 2003 Saturn L200 automatic with the 4-cylinder Ecotec engine and the best it could average per tank was about 29 MPG. That was with Mobil-1 5W30, K&N air filter, driving at 55 MPH with the cruise control whenever possible, minimal use of the AC, windows closed, and tires properly inflated. Most fill-ups averaged around 27 MPG.

Meanwhile I knew others driving late Saturn L300 automatics with the V6 engine were getting about 27 MPG on a consistent basis too.


So we chose the smaller engine, and compared to the V6 version of that car we had worse acceleration and the same average fuel economy - rather than worse acceleration and better average fuel economy.

Needless to say we don't have that car anymore, and this was one of maybe 20 reasons why. Way to go, GM!



I have found over the years that some of the larger engines get better fuel economy than the smaller ones simply because they are at such low rpm's when cruising. Good example is many of the GM 3800 cars. Some of those big boats will easily get into the 30's on the highway while many 4 cylinders are working so hard to keep up that their fuel economy is terrible.

 

[abycat]

My dads 2010 ss cobalt 4 door gets low 40's on the highway and its a turbo. It gets pretty good mpg around town too.

 

[itguy08]

Work an engine harder and it will get worse fuel economy. You needs certain amount of we're to do a certain amount of work no matter the calendars,

Case in point, throughout college I had a 1986 Mustang with a 2.3 and 4 speed stick. It made 88 hp and 1 something lb ft of torque. Driving it was almost always pedal to the floor to get somewhere and it buzzed along on the highway. Got about 300 or so miles to the tank.

Got out of college and found a smoking deal on a leftover 1997 Mustang Cobra. 4.6L v8, 305 hp, etc. Didnt have to get on it to go. And guess what? 300 or so miles to the tank. IIRC the gas tanks were the same size on both cars

 

[k24a4]

In 60/40 hwy/city over the last 35000 the Honda I4 (k24) has averaged 30.9 mpg according to my data on Fuelly. I expect it to go up since during this time I had an emissions issue and a frozen rear caliper. I think this avg is pretty good given the Accord's weight and power. All hwy is consistently in the 34-36 mpg range durong the warmer months. Car is manual trans.

71chevyguy I'd expect your mileage to be better. Car still breaking in?

 

[rjundi]

My wife's 20005 Legacy GT wagon fall into this category. Its 2.5L turbo flat four manages EPA of 19city/23highway. Her driving style she gets 23.5 average.

The 250HP motor is really nice with wonderful mid range punch coupled to a 5 speed manual.

 

[GearheadTool]

Originally Posted By: rjundi
My wife's 20005 Legacy GT wagon fall into this category. Its 2.5L turbo flat four manages EPA of 19city/23highway. Her driving style she gets 23.5 average.

The 250HP motor is really nice with wonderful mid range punch coupled to a 5 speed manual.


Just found out mine will be a 162HP DOHC 5-speed, not a 140HP auto (possible SOHC.) And even that one had good power. Im giddy. Im getting a 97 Legacy Outback.

 

[pair of Blazers]

the KIA Forte I just bought has an EPA of 37 hwy and the best I've gotten out of it is 33. to be fair though I haven't cracked 10K miles yet. I would like to see what would do on a trip to say cape may from NYC. I think it might do a little better.