lol, interesting discussion to read!! I think Manybrews has a good point with his theory, but doesn't the load on the rear differential when engaged in 4WD have an impact on the rest of the driveline?
I think Manybrews will agree that the slightly better fuel efficiency in 2WD doesn't really justify the additional cost of designing and implementing an intelligent 4WD system in an SUV... I think it doesn't really add much value in comparision with a hybrid car setup. Of course the latter costs much more money to develop, but on the long term... the only way to get MPG down

 

I have to admit manybrews made the light bulb on top of my head come on, and I do understand what he is saying now, but I stilldont think the only reason they would put that 2WD function there is just because of customer request, there has to be something we dont know or are not getting behind the system. After all the manual does state "2WD= better fuel economy" and it really offers that to a certain extenct, in the city at least.

 

trust me, the main reason its there is because customers requested it. For whatever reason, a lot of people have their heads in the sand over AWD, as though it would be beneficial to be able to shut it off. Many people complained that the old Outie was either 2WD or AWD, with no choices.
Well, they implemented the choice just to make people happy, but its not the same as on an old pickup truck... On MOST 4WD trucks, the front axles, differential, and driveshaft do not spin unless in 4WD. On this setup everything is spinning, but there is no torque transfer from the spinning propshaft to the pinion of the differential due to the electronic clutch that is placed between the two. Even the clutch plates are spinning! there just isnt any friction between them, similar to having your foot on a clutch pedal whilst the engine is running.

heres an example of a Haldex AWD coupler, which is nearly identical in operation to mitsus system. The part in green is the clutching mechanism. In 2WD on an outie, the clutch is totally disengaged, so you can see how no torque will be transferred. But you will also see that in fact every componant is spinning at whatever road speed/transfer case speed is present.

 

I am no engineer, just a thinking average Joe, and the article on the 4WD system of the Outlander (found HERE) is more than enough for me to understand that 2WD offers the best fuel economy. People argue some of the features of this vehicle are gimmick (e.g. paddle shifters, 2WD mode, 4WD Lock which isn't truly a "locked" mode), well, to each his own I guess. But I still go by the words of the manufacturer, since they made the vehicle, they probably know more about it than anybody else.

Fuel economy between 2WD and 4WD Auto is a moot point to argue about. Unless maybe you work for the EPA and you have access to a lab that can truly scientifically measure the fuel consumption between the 2 modes under strict controlled environment. But running your car on the road and saying you got it figured out, hmmm, I doubt it. Although I would agree that the margin of fuel economy will be slim, and perhaps it would only become practical after 4 to 5 full tanks. So driving your Outlander in either modes, in a real world stop-and-go traffic, will not give you practical savings to prefer one mode over the other. But despite the impracticality of it, there being no "tangible" savings using either modes, it's never a point against a "gimmick" 2WD mode. The 2WD mode does it's job of being the best fuel economy mode (although by a hairline margin). The point of contention should be the great fuel economy the 4WD Auto has to offer. It's so efficient in giving you the right torque at the right conditions, and does that while maintaining a fuel economy close to driving in 2WD mode. Isn't it great you can actually drive in this mode and yet get mileage as if you're on 2WD? And that's why I guess Mitsubishi labeled it as the "default" mode on this vehicle. What if there was a big gap in fuel economy between 2WD and 4WD Auto? You'd be forced then to use 2WD just to maintain your great mileage. Me, I'm just thankful I get to drive my Outlander in 4WD Auto mode and yet save on gas.

 

Hey "Manybrews"!
Doyou own a '07 XLS 4WD?
Or, are you just speaking your mind based on your own theories?

All the '07 XLS 4WD owners seem to agree with each other based on experience.
You seem to be getting kinda sensitive about the whole subject.
Just curious...Take care!

 

Uhhm, I don't think MB is speaking based on "his own theories". He happens to know the mechanics inside out for a very good reason. His whole point is there is no actual difference between 4WD and 2WD mechanical load. As he rightly states, there is no significant difference in fuel economy under identical test conditions.

However, here is MY theory on why there may be a perceptible difference for a lot of people:

1) People believe they have two different systems, 2WD and 4WD with most people believing from past history and knowledge of 4WD systems that there is additional load.

2) Because people believe there are two different systems they instinctively select 2WD for most "normal" driving and 4WD for when environmental conditions warrant. These conditions typically contribute more to the poorer fuel economy notthe drive system.

3) Older 4WD systems were perceived to have noticeably less power than 2WD so driving habits are affected as well - i.e. more lead foot syndrome.

4) Mitsu's statement in the owners manual that you will experience better fuel economy in 2WD I think has more to do with Mitsu understanding the consumer's built in habits and mindset, at the present time.Perhaps they should have consideredsomething like:

"We at Mitsubishi understand that you as the consumer do not have the capability to understand new technology. Even though we have built one of the most technologically advanced all wheel drive systems in the world, we have given you the option of shutting down the rear wheel drive system to satisfy your ignorance rather thanexpecting your pea-sized brain to rationalize how a vehicle could get the same fuel economy and ride in 4WD versus 2WD. However, because you are a loyal customer we will agree that in certain conditions, you may experience better fuel economy in 2WD versus 4WD. Forexample, if you drive in 2WD when it is a cool summer day you will likely experience better fuel economy then when you drive in 4WD in the middle of a blizzard in December. Another example would be, if you drive in 2WD at 55mph for one hour you will likely experience better fuel economy then if you drive in 4WD at 80mph for one hour.

At Mitsubishi, we care. Even though we have some really smart engineers, you can be rest assured we always try to adhere to the laws of physics."

[sm=roll.gif]

 

I have a question, doesnt running it in 4WD lock generate more heat and possibly damage the transfer asm running 70mph on the freeway?

I have a 93 Chevy 4x4 I know it will damage the 4WD with extended driving on dry pavement. I know the newer systems are different but basically my Chevy is turning the entire time but when 4WD is engaged it actuates a largesolenoid that moves the drive to the front axle. I do notice a difference in performance however to burn enough gas to know mileage dif I havent been able to but I can tell from engine RPMs that it is using more gas.

 

That's right. Mitsu doesn't recommend 4WD Lock mode on dry pavement. But they speak more of tire wear than mechanical damage. I'm pretty sure the mechanical stress on the transmission is going to be high. And that's why on dry tarmac I drive 2WD always, especially in twisty areas.

 

Actually in the twisties we have here, low speed 10-15 mphand super tight the 4WD makes the handling even more superb in fact it rocks. It latches into the turn and flies.

The roads are so bad I have to take them easy on thesport bikebut in the outie I get to really enjoy them.

If you want to have some interesting fun and can handle a vehicle slightly out of control take off the traction control and put it in 2WD it squealsthe tiresand slides around in the gravel thats piled in the road.

 

you do realize ive worked for mitsu for 16 years, right?