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1658 Views 16 Replies 11 Participants Last post by  Mr X
Sorry if wrong place BUT... I have a question. As most new Volt drivers are... I'm becoming obsessed with the best mileage. I will be about 75/25 electric/"fuel" miles. What is the optimal speed to "drive gas"? I'm sure highway is probably the most efficient time to use hold correct? Is there an optimal speed? 60, 65, 97, 70? I'm sure flat vs hills, slow grades vs steep all make a difference I'm just currious. Btw I've got about 70miles on gas and I'm at 40.2 :) around 215ish overall mpg with somewhere around 350 miles +-20.

Loving it btw :)
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The third graph in the post here provides some insight. Regardless of power source, efficiency drops at speeds above 55mph primarily due to air resistance.

The Volt is most efficient between 20 and 36 mph. For overall best efficiency use EV mode for driving at all speeds until the battery charge is depleted (contrary to my example below) and then use gas. Hold mode can easily exceed the EPA mpg estimate of 42mpg combined. You want the gas engine to reach full operating temperature for best efficiency, monitor the engine coolant temperature and you will see it stabilize at between 185 and 205 F, then it has reached full operating temperature.

If you consider the cost of electricity in your area then at current gas prices EV mode and when using gas may be within 1 cent per mile of actual cost. The last time I calculated this in my area the cost was 4.5 cents per mile EV and 5.5 cents per mile gas.

I usually try and hold my highway speed to no more than 62 - 65 mph (EV) and 65 - 70 mph (gas).

On a recent trip I traveled ~70 miles (60 miles highway and the rest secondary roads): 55 miles EV and 15 miles using gas. The Volt displayed 54.7 mpg (gas) but I am sure this included additional miles due to regeneration. I used Hold mode for part of the way (both going and on the return trip) as I like to arrive home on battery power. My Volt still had approx. 4 miles of EV range when I arrived home so I could have traveled a bit further on battery than I did. The air temperature was in the 70s. The Volt showed a combined MPG of 250+

The unused battery capacity (approx 1 kwh) was not wasted, the Volt recharged in 4 hours instead of 4.5 hours it would have taken if the battery had been fully depleted. I estimate I used an additional 9 oz. of gas to travel the extra 4 miles on gas instead of battery.
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Thanks for all the responses everyone!

My scenario was I was about 5 miles short of EV and I couldn't decide if it would be better to use the gas on the highway and EV on the backroads.

I also wondered if using mountain mode was a good idea when I was out of EV, for say 10 miles on the highway or backroads, to build up slightly for the last couple miles from the off ramp to my house.

Sent from my SM-G900V using Tapatalk
In the 2016 and 2017 Volt Mountain mode will build up approx. 2 bars (20%) of battery charge. Use it if you have exhausted the battery, at least 20 minutes before you plan to start a long ascent. Mountain mode will use more gas, perhaps 20% more, than the gas engine would otherwise use while it builds up a charge. It is more efficient to let the Volt automatically switch from EV to charge sustaining mode (gas engine) as the battery becomes depleted or manually select Hold mode while you still have some remaining battery range that you prefer to save for later use.
Whatever warm weather driving routine you settle on will be disrupted by winter temperatures. Battery range will drop an estimated 20% or so, that is without using the climate control system's electric heat.

If you have level II charging at home then you will want to precondition the Volt in the morning so it is warmed up when you leave. Use the electric seat heater and steering wheel heater (if equipped) as this uses very little energy. Use of Engine Heat Assist is a personal choice. This will start and cycle the gas engine on and off but it uses very little gas and effectively heats the cabin. By default Engine Heat Assist activates when the outside temperature drops below 35F. You can defer Engine Heat Assist until the outside temperature drops below 15F.
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