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Discussion Starter · #1 ·
I am sure that I have read on these forum threads and elsewhere that using Mountain Mode (MM) as a means of re-charging is not economical.

On a longer journey today, I engaged MM when the displayed range was down to just four miles and I had already used up 9.6 kWh from the battery. I continued to drive normally until the battery was back up to approximately half capacity with the displayed range now at 20 miles - at this point the ICE stopped running so I switched back to NORMAL. I then continued to drive until I had used up all the ICE range. The total distance covered with power generated by the ICE alone was 31.5 miles (just over ten miles with the ICE running and the remainder using battery power that the ICE had generated) and during this time the ICE consumed 0.55 gallons of fuel. That is an average fuel consumption of 57 mpg.

Which is pretty impressive - and slightly better than I was getting with my previous vehicle, a diesel powered VX Astra.

At local petrol prices, the cost of those 31.5 miles works out at £3.02 or £0.096 per mile. At my current home electricity tariff, of £0.14657 per kWh, and given that there is a charging loss of approximately 20%, the cost of covering the 31.5 miles on battery alone would have been almost half as much but I reckon that if I had to charge at a public charging point the cost could well have been more.
 

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Recharging using MM whilst driving, then switching back and using it all up makes no difference to just continuing to drive after the battery is empty and letting the car do it's own thing.
All MM achieves is pre-filling the battery by running the engine harder whist driving to build up a decent buffer (50% of the usable capacity) ready for you to climb the next mountain.

The best use of MM in my opinion, is a completely different use case, of enraging MM when setting off with a full battery on a journey that's beyond battery range, especially if that journey involves a stretch of motorway or dual carriageway. The car will run on battery until it drops down to 50%, at which point the engine keeps the battery around 50% charge. You'll see your remaining battery range fluctuate by a mile or two as you're driving. Note this range figure.

When the remainder of your journey is roughly the same as the remaining battery range, switch back to normal. All being well, you'll arrive with near enough 0 miles remaining on the battery.

The purpose of doing this is to use the engine for generating charge whilst on the faster stretch of your journey. This is because it's more efficient at generating charge at motorway speeds than at low speeds (as I understand it). The other benefit is that the start and end of your journey is usually in an urban environment - housing estates etc, and it's more pleasant and socially acceptable to not be running your engine in these locations, but to concentrate your engine use on the less densely populated motorway sections.
 

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As they say "YMMV".

Literally.

It very much depends on the sort of route you are doing. I tested this extensively and there are some scenarios where it is slightly more economical to run MM, but this should be done from around 25% to 50%. Going lower and then hitting MM means the engine revs higher and is less efficient.

The economy benefit of using MM rather than 'HOLD' or 'NORMAL' (which function in exactly the same thing, but simply at a different battery SOC) is that the engine is not shutting off and restarting which, in itself, introduces efficiency losses.

So, for example, if you are traversing undulating terrain where the engine would normally shut off on the down grades, MM will keep the engine running.

It depends on what you want. Another benefit is that if it is cold weather MM can offer more consistent warmth on shorter journeys (a commute home from work, for example). But it is also more intermittent on longer ones whereas HOLD will be on-off more periodically so on a longer trip HOLD is better for winter heating.

It's a mixed bag, I am afraid. The absolute bottom flat out best economy is, in my tests, to use MM in the 25% to 50% regime, but you would be hard pressed to spot the difference to any other operating conditions.

Just let the car figure out what it wants. It is not perfectly ideal, but you're unlikely to do much better.
 

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Discussion Starter · #4 ·
I appreciate that other drivers may enjoy different results. What has impressed me is the overall economy even when using the ICE - I expected a significant efficiency loss (based on my experience with larger scale diesel-electric motive power) but the Ampera in all modes seems to be relatively efficient. Of course the real benefit is that I have an electric car that, for most journeys, runs on pure battery power but when I do make a longer journey, I am not constrained by the availability and cost of public charging points.
 

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It has (effectively) a lock-up feature, and two motors that reconfigure for different conditions. DMUs are usually 'always' serial hybrids, the Ampera will run parallel or serial.

The only other car that can do that is the Outlander, but it is a more primitive system. The Outlander mates the engine to the driven wheels via a fixed gear.

Ampera is therefore the only car I am aware of that can do both serial or parallel-with-CVT-gearing, and the objective and purpose of all that engineering-flammery was so owners can then remark how efficient they find it!
 

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I appreciate that other drivers may enjoy different results. What has impressed me is the overall economy even when using the ICE - I expected a significant efficiency loss (based on my experience with larger scale diesel-electric motive power) but the Ampera in all modes seems to be relatively efficient.
When my charge port failed on my Amp I did a 70mile round trip 95% motorway and 5% in town and with a completely empty battery managed 46mpg, pretty much the same as the Fiat I had before would've done on the same trip. So even lugging around all the extra weight its not bad, saying that of course a Prius on the same journey would've been significantly more efficient but then a regular Prius can't match the 150mpg I get on my regular commute when Amp is fully charged :D
 

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I think this is one of those things that ought to be filed under 'Just because you can doesn't mean you should". Yes, I've tried it too, but my conclusion is that it's best to leave the car to work as the designers intended. Against the 200mile+ offerings of today, the Ampera's electric range seems puny, and it's natural to want to extend it as much as possible. But we have to remember that this car was designed to run out of battery power and to deal with that situation gracefully, which it certainly does. Quoting from Larry Edsall's book, Bob Lutz apparently had a hard time explaining it to his executive colleagues back in 2006 "Look guys, you don't understand. This is not about maximising range or getting maximum efficiency. It's about permitting the average American to drive electrically most of the time ... but if my mother is in bad shape in Chicago, I don't have to turn around and get my other car - I can just drive to Chicago.... That's what it is about"
 

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I use MM on long distance trips as it gives me an emergency reserve just in case the ICE suffers a failure. It would allow me to drive to a rest area or perhaps even a garage. If I encounter a large traffic jam I flick it to normal and run the battery down , then back to MM when the jam is over. When I am nearing my destination and the range matches the battery range I flick it to normal and use up the last of the battery.
 

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FWIW MM is by far the most ecological for journeys with known town use either end.

My commute home I could run MM until 'just there' on the motorway, and then go back to normal. That charge which MM set was just the right amount then to get me home electric only without dispensing fumes on the final urban leg.

If one were to run 'normal' then one would run out of battery on entering the urban area and then chuff chuff all those fumes into the city having been greener-than-green out on the motorway where no-one is affected from localised emissions anyway.

The stop-start of the engine through the urban interval is also less efficient than just running steady on the motorway before 'powering down' the engine.
 

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Discussion Starter · #10 ·
FWIW MM is by far the most ecological for journeys with known town use either end.

My commute home I could run MM until 'just there' on the motorway, and then go back to normal. That charge which MM set was just the right amount then to get me home electric only without dispensing fumes on the final urban leg.

If one were to run 'normal' then one would run out of battery on entering the urban area and then chuff chuff all those fumes into the city having been greener-than-green out on the motorway where no-one is affected from localised emissions anyway.

The stop-start of the engine through the urban interval is also less efficient than just running steady on the motorway before 'powering down' the engine.
I think that pretty well sums up the advantages of driving an Ampera . . .
 
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