Use 2wd unless conditions need 4wd.

Check the user manual as that will probably say the same.

Driving the extra drivetrain is wasteful on fuel, which is why many (often older) 4wd have autolock hubs either original spec or aftermarket.

Just to be clear, there are hub locks which can be auto or manual and are fitted at the wheel end of the front axle, which means that the front wheels can rotate without having to rotate the front diff, halfshafts and prop shaft back to the transfer box.

Locking diffs have also been around a while, with the most common being a locking centre diff only. There are some vehicles that have locking diffs front and rear but that can cause more serious damage on hard surfaces (seen locking diffs explode due to the forces applied when tires don't slip...).

There are also viscous couplings used which may or may not have fancy electronic control. These tend to be very expensive when they break...

i do 2WD inside the city roads + 4WD when i am out side the city, i do not do off roading

You'll get better performance and efficiency in 2WD mode, especially on faster roads outside the city.

You should leave it in 2WD unless there is ice or snow on the road.

If you live in a country where roads outside the city are mostly slow bumpy gravel or loose-dirt roads, then you should use 4WD and low speeds on those bad roads.

The Renault/Dacia Duster uses the same 4x4 system as Nissan

The Duster is offered with two-wheel drive or four-wheel-drive. The 4x4 variants make use of Nissan's all-wheel drive system,[10] which allows the driver to choose from three different driving modes: Auto, in which the rear-wheel drive is engaged automatically in case the front wheels lose grip, Lock, whereby 50 per cent of torque is consistently fed through the rear axle, and 2WD where the transmission is locked into front-wheel drive for maximum fuel efficiency.

From the Duster's user manual:

"AUTO" mode automatically distributes the engine torque between the front and rear axles according to the road conditions and the vehicle speed. This position optimises road holding. Use this mode on any type of road (dry, snow-covered, slippery, etc.) or when towing(trailer or caravan).

"2WD" mode. Operating principle The "2WD" mode uses the front wheels only. Use this mode on dry roads with good grip

Operating principle "4WD Lock" mode distributes the engine torque between the front and rear axles in order to optimise the performance capacity of the vehicle in off-road situations. This mode should only be used in extreme driving conditions(mud, steep slopes, sand). Note: if the vehicle speed exceeds 36 mph (60 km/h) in 4WD Lock mode,the system automatically switches back to AUTO mode.

You shouldn't feel any significant performance difference between 2WD and 4WD under normal conditions, the Duster is not a high performance car and you probably won't drive it at high speed on slaloms. If anything fuel consumption can be a bit higher with 4WD turned on, and the transmission would have a bit more wear.

As stated above using Lock mode CAN harm your car, more wear and tear on the tires and transmission, but most chances are that you are not really using it since it disconnects itself at 60 KMH.

The handbook I looked at is slightly different than @JdeBP mentioned, but here's a qoute:

All-wheel drive system– Irrespective of the mode selected, do not start the engine if one or more wheels are not in contact with the ground(eg. when the vehicle is on a jack or roller bench).– Do not turn the mode selector when cornering, reversing or if the wheels are spinning excessively. Only select the"2WD", "AUTO" or "4WD Lock" mode when the vehicle is being driven in a straight line.– Only use tyres which meet the required specifications.– "4WD Lock" mode is reserved solely for use off-road. The use of this mode in any other conditions may adversely affect thevehicle's manoeuvrability and damage its mechanical components.– Always ensure tyres with identical specifications are fitted to all four wheels (brand, size, structure, wear etc.). Fitting tyresof different sizes to the front and rear wheels and/or left and right wheels may have serious consequences for the tyres,gearbox, transfer gearbox and the rear differential pinions

To summarize as other mentioned, use 2WD unless you are driving in heavy rain, snow or ice and read the driver manual.

1. Don't use "Lock (4WD)" mode unless on soft terrain.

You will get increased wear of tyres and transmission, worse directional stability and higher fuel consumption for nothing in return.

There is an automatic function that disables "lock" at high speeds, but it is only a safety measure and not a replacement for a reasonable driver choice.

"Locked" 4WD car handles turns impressively bad, up to and including a complete loss of directional control and going out of the lane or road.

"Locked" is only for sand, mud or some cases of snow and only for use below 30km/h.

2. Auto is good everywhere. That's why it is called "Auto". It may fail to engage rear wheels hard enough when the terrain is especially bad (mud, sand, heavy snow) and that's why "Lock" mode exists.

3. 2WD is good on hard, clean, dry, paved road. You will get about 1 litter per 100km better economy in exchange for slightly worse start from still. It runs almost like any other front-wheel driven car.

I will offer a counter-point to all of the current answers which indicate using 2WD "except when you need 4WD".

In general, I will agree that 4WD isn't necessary and the 2WD (front wheels driven) mode is sufficient, as is attested by the fact that the majority of vehicles built today are front-wheel drive.

However, "when you need" 4WD could be in an emergency situation where the ability of having the rear wheels powered can help with handling (note: this means acceleration or cornering to avoid the accident, not braking - 4WD does nothing to improve braking^*), thus, potentially avoiding an accident. Therefore, I'd suggest leaving it in "Auto" mode all the time.

According to the Wiki article (as originally linked by rsf) Auto distributes power as needed. In an emergency situation, there often isn't time for the driver to remember to hit the 4WD button/switch to say anything of actually hitting it.

Additionally, while it's a nice idea, most people won't remember to switch to "Auto" or "4WD" on a rainy or snowy day, thereby completely negating the purpose of lugging around all the extra hardware (and reducing fuel economy all the time by having a heavier vehicle).

If fuel efficiency is of significant concern (and I'd suspect it's less important to this OP, who specifically chose the model with the larger engine), I'd recommend doing a bit of personal testing, keeping track of your mileage (kilometerage?) for a month (or at least 2 full tanks of fuel) using 2WD mode, then a month using Auto mode to see if there's a significant enough difference to you. Your efficiency may will vary from officially published numbers, so test it out in your regular driving routine. Some may be willing to sacrifice 10% fuel economy for the potential safety benefits, others may be willing to sacrifice more, and others less. My bet is that the difference between 2WD and Auto mode will be negligible, while full-time 4WD would be more noticeable.

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^* The lack of effectiveness of 4WD on braking is evidenced by the number of 4WD vehicles I see in the ditches during the winter where I live in the Midwest US vs the number of FWD/RWD cars I see. People seem to think 4WD/AWD makes them invincible on snow & ice. It most certainly does not.

The labelled "Auto" mode on a Duster is a "smart" 4WD mode. (For want of a better term.)

Leave it in "Auto" and forget it forever.

There's almost literally NEVER a need to select "2WD!".

(Indeed, it's a bit silly they bothered to include a "2WD!" mode.)

So, like, 50 years ago folks would say things like,

• Don't leave your auto in "D" at the traffic lights!

• Check All Fluid Levels if you leave your vehicle parked for more than 2 days!

• Learn these Hand Signals in case the Relay on your Indicators breaks during Driving!

It's all unnecessary today.

It's impossible you could notice any (say) efficiency difference in 2WD mode.

Dangerous to muck about with...

Indeed let's consider this hypothetical:

An imaginary "better braking system" ...

Say that your car had two "braking systems".

You have "normal" brakes, and also "better" brakes.

Incredibly, there's a switch between "normal" and "better".

It comes from the factory on "better".

You hear that in theory if you select "normal" it will save a penny a day.

Would you ever select "normal" brakes?

The analogy makes it clear that, in a Dacia Duster, it's great to just leave it alone on "Auto" which is "smart" 4WD.

In a traditional 4x4 vehicle like this 4wd will only benefit you in gaining traction on a loose surface. Use 4wd when youre stuck or there's wheel slip otherwise it just extra fuel youre using. Find a safe place to try it out. The low range gives you more torque which is helpful when climbing a steep grade or when the snow/mud/sand is thick enough that you don't have the power to drive through. Most people don't need these features and the manufactures have learned this by making crossover suvs that reflect how people really use their trucks. If you do live somewhere with rough terrain the old 4x4 is awesome.

Many people just don't get it...

There are only two positions you should be using for the way you described your driving, 2WD and AUTO. 2WD will save gas mileage and wear and tear on the driveline. Auto sets the driveline into all wheel drive. This is meant for better control on road and for inclement weather, such as wet pavement and snow.

Lock should never be used on-road as it will mess up your driveline in short order, especially if you have a manual (stick) transmission. The only time you would engage lock on road is if the road is so snow-covered that your tires are running on fresh snow and not even touching the road surface and auto just isn't helping. In this instance, it's just like driving on loose soil or sand where there isn't a prepared roadbed. If you are driving on hard-packed snow use Auto.

Here is a hint from a hardcore four-wheel-drive vehicle owner and builder: my jeeps are built up for serious offroading and in over fifty years of driving and playing off-road, even teaching my daughters to drive in mud fields before they were old enough to get their learners permits, the big point is you never use Lock except to get out of what the other options you have got you into.

If you are stuck, and you are in Lock, you now have to pay someone to get you out. That is unless the road is so bad with snow as I previously stated and you have no choice, in order to find away off the highway, to somewhere safe, to wait it out.

Bear in mind, my tires are four foot tall and made for stuff like this, I've even gotten phone calls from the local police during blizzards asking me to come pull squad cars out of ditches because of the way my jeeps are built, and the towing service they have a contract with won't come out.

We live on the shore of one of the Great Lakes, just below Canada, in the US, in the blizzard zone, and I don't mean Dairy Queen! Over stressing light equipment will damage it. Your car is light equipment, and driving on pavement in lock is putting extreme stress on it. Never admit to doing it to a dealer or authorized mechanic as it will void your warranty.

Those gears and all gears should be used once in awhile. My opinion is, if something isn’t used for a long period of time it or they can go to hell! Like gaskets or! On automatic transmissions the fluid is ran through the system better when you use the gears. Just like checking your automatic trans. You Change gears as the engine is running so the fluid will run thru the system better and then you check it! Change gears once in a while! Just my opinion! Won’t hurt!