Mountain Mode Versus Hold Mode Explanation

[Automobiles]

Mountain mode either maintains the current battery state if it's over 50%, or regenerates it back to 50%. Regenerating it back to 50% is a very inefficient use of the ICE as a generator, so Mountain Mode is by far best used when you already have 50+% left.

In Hold mode, it will allow the battery to support the ICE when accelerating up to about 2.5% of the battery charge; this means it'll get you up to speed reasonably well in most circumstances without the ICE having to work too hard.

In Mountain mode, it will do the same, but with a buffer that's more like 5%.

This means in normal driving without long hills, you won't notice any real difference between Mountain and Hold modes.

However, on longer hills such as on the motorways and A-roads in Devon/Cornwall, the Lake District, etc., the 2.5% of the Hold mode is very quickly depleted and the ICE then has to rev hard to keep the car going at normal speed; revving hard = inefficiency remember. In Mountain mode, the extra buffer size means that the ICE doesn't have to work so hard, and it's therefore more efficient.

An extreme example of this would be some of the really long motorway hills where the ICE simply can't maintain 70mph - it's only an 86ps 1.4 dragging a 1.8 tonne car after all - and at that point in Hold mode the car will lose speed. In Mountain mode it will be able to keep going for longer, hopefully to the top of the hill 

Mountain mode doesn't really mean "Going up a 1 in 4 hill", it means "Going up long hills at high speed".

So... basically I believe Mountain mode is best used on trips where there are long hills at high speed, in which case turn it on when you have 50% of the battery left, then when you get within about 15-20 miles of your destination, switch back to pure EV (Normal) mode. If you've got much less than 50% left, or the hills aren't that long, stick with Hold mode.

I noticed significantly lower revs and more battery push using Mountain mode than using Hold mode when going to/from Cornwall at 70mph.

- Richard G