The only times I would use W is when traction is limited , leaves, mud, ice/snow gravel........ Or when my mother is in the car!!
Being a diesel it will have most of the engines torque on the lower end of the rev range. Diesels have more grunt & pulling power down there than petrols. I don't know for a fact, but an educated guess would be optimum torque around 2500 - 3000 rpm. Basically where the rev counter is when the car starts to shove you into your seat
If we are talking economy without a heavy right foot then W or the C mode will be very slightly more economical, and perhaps more relaxed
The secret though is more to do with forward observation and anticpation which will when applied properly should save far more fuel than the different modes. Our big engines have wonderful torque that will very quickly get our chariots up to 30mph without overly pressing down on that right pedal, plus these big engines will comfortably pull away in second gear.
John
tend to drive, shall we say, a little more sedately, hence the reason for selecting W.
Everyone has their own driving style. I'm with those who leave the gearbox in S except when conditions are very slippery.
I prefer the sharper getaway of a first gear start. If you're driving on a light throttle then the car changes up to second fairly quickly in any event. On the other hand if you need to move quickly to fit into a gap in traffic then the car is already in the right gear. Just my view of course.
