FWD vs RWD vs Gas Economy

Muscle Master · 09-15-2008, 01:33 PM

So what gives, why does FWD gives better economy then RWD I don't understand, Chrysler and GM did good with MDS and AFM with the V8's but I would like to see more RWD V6's around, at least make them AWD

Would someone explain

The_Stache · 09-15-2008, 02:17 PM

AWD dramatically reduces gas mileage (look at subi's), Same goes for 4X4.

Studies have proven that an exact car engine, weight, cod etc in both FWD and RWD will give the mileage to FWD by 1 MPG. The problem is that RWD cars are generaly not built equally when compared to FWD cars..

Mblock66 · 09-15-2008, 02:27 PM

It has to do with the drivetrain loss in RWD as compared to FWD. It is easier to get the power from a front engine car to the front wheels of that car. There is less driveshaft and other parts for the power to get to the wheels. I mean we are talking a really small amount here so I would agree it might be like 1 mpg that a fwd car could use more efficiently then a rwd.

It would be interetsing to see if a rear (mid) engine car with rwd came out the same as a fwd front engine car.

*radz28* · 09-15-2008, 02:52 PM

Quote:

Originally Posted by Mblock66

It has to do with the drivetrain loss in RWD as compared to FWD. It is easier to get the power from a front engine car to the front wheels of that car. There is less driveshaft and other parts for the power to get to the wheels. I mean we are talking a really small amount here so I would agree it might be like 1 mpg that a fwd car could use more efficiently then a rwd.

It would be interetsing to see if a rear (mid) engine car with rwd came out the same as a fwd front engine car.

I believed typically RWD components, on the whole, add more weight. In addition, there are more components and any time you have power going through gears you have parasitic loss. It's my understanding FWD trannys can combine and integrate the differential, ring gear and such together with the transmission, which overall, makes it a little more efficient. I think it's mostly less weight though.

Mblock66 · 09-15-2008, 04:06 PM

Well less weight would be an outcome of less parts sure. But I think the parasitic loss (which is what I was trying to get at in my post) might have at least as much to do with it as the weight. If you don't need as much throttle at 70 MPH b/c an engine can be more efficient and put more power to the ground in a FWD then in a exactly equal RWD setup it would save fuel.

That is my understanding at least

camaro&T/A · 09-15-2008, 06:19 PM

also, from my understanding you can pull something for longer than you can push it, and you can push something faster than you can pull it

Kyle2k · 09-15-2008, 06:24 PM

Basically the lack of fun is compensated by 1mpg...

stovt001 · 09-15-2008, 07:07 PM

FWD powertrain layouts are more compact than RWD layouts. Therefore you can get the same interior space into a smaller car with FWD.

09-15-2008, 02:17 PM	#2
The_Stache SoCal Race Team #13 Drives: 2010 1SS:RS:LS3:SW Join Date: Mar 2007 Location: Gilbert, AZ Posts: 1,800 View My Garage	AWD dramatically reduces gas mileage (look at subi's), Same goes for 4X4. Studies have proven that an exact car engine, weight, cod etc in both FWD and RWD will give the mileage to FWD by 1 MPG. The problem is that RWD cars are generaly not built equally when compared to FWD cars.. __________________ A.K.A - Diarmadhi (old handle) - So much to do.. So little money Owner : Fast-Stache Industries LLC

09-15-2008, 06:24 PM	#7
Kyle2k LVL 50 Troll Stomper Drives: 2010 Camaro Join Date: Feb 2008 Location: Indianapolis Posts: 3,463	Basically the lack of fun is compensated by 1mpg... __________________

09-15-2008, 07:07 PM	#8
stovt001 Drives: 2006 Cobalt, 2004 Taurus wagon Join Date: Oct 2007 Location: California Posts: 3,810	FWD powertrain layouts are more compact than RWD layouts. Therefore you can get the same interior space into a smaller car with FWD. __________________ "It's kind of fun to do the impossible" - Walt Disney There's a great big beautiful tomorrow shining at the end of every day There's a great big beautiful tomorrow Just a dream away

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09-15-2008, 02:27 PM	#3
Mblock66 Drives: 2005 Subaru Legacy GT Join Date: Jul 2008 Location: NJ Posts: 312	It has to do with the drivetrain loss in RWD as compared to FWD. It is easier to get the power from a front engine car to the front wheels of that car. There is less driveshaft and other parts for the power to get to the wheels. I mean we are talking a really small amount here so I would agree it might be like 1 mpg that a fwd car could use more efficiently then a rwd. It would be interetsing to see if a rear (mid) engine car with rwd came out the same as a fwd front engine car.

09-15-2008, 04:06 PM	#5
Mblock66 Drives: 2005 Subaru Legacy GT Join Date: Jul 2008 Location: NJ Posts: 312	Well less weight would be an outcome of less parts sure. But I think the parasitic loss (which is what I was trying to get at in my post) might have at least as much to do with it as the weight. If you don't need as much throttle at 70 MPH b/c an engine can be more efficient and put more power to the ground in a FWD then in a exactly equal RWD setup it would save fuel. That is my understanding at least

09-15-2008, 06:19 PM	#6
camaro&T/A Drives: '82 Z28 400SB Join Date: Aug 2008 Location: Plover WI Posts: 172	also, from my understanding you can pull something for longer than you can push it, and you can push something faster than you can pull it