[dennis]

Having driven 620 miles on my Karma, I decided to look at its cost per mile and compare it to my prior daily drivers. About 40% of my driving is on the freeway and 60% around town. 2/3 of the days I drive less than 30 miles and don't use the ICE.

With premium gasoline at $3.93/gal. and electricity at $.20/kwh in California, my cost is $.18/mile. Under the same driving conditions that compares with previous daily drivers:

2006 BMW M5 (12 mpg) - $.33/mile
2008 Lexus LS600 hybrid (17 mpg) - $.23

Plugging in the national averages for gasoline ($3.65) and electricity ($.115), my cost could have been $.135/mile.

Conclusions:

1) Hybrids are cheaper to operate, especially PHEV's
2) California is expensive
3) Your costs and mileage may vary
4) I'm a nerd

 

[kabalah70]

dennis, nice. Huntsville is much closer to those national averages. Nerds rule the world, just look at Bill Gates.

 

[SoCalGuy]

In pure electric mode, wouldn't you see closer to $0.13 per mile (20.1kWh x $0.20 / 32 miles) or as little as $0.08 per mile (assuming 50 mile range)?

 

[ffcars]

How many kwh does it take to charge the car? In other words, what's our cost to fill up with electric?

 

[ct-fiskerbuzz]

How many kwh does it take to charge the car? In other words, what's our cost to fill up with electric?

It's roughly 20 kWh (depends of course how "empty" you have the battery when you "fill up"). The cost depends on what electricity costs you (personally) per kWh, which varies widely around the country. Mine is roughly $.10/kWh, or $2 for a "complete fill".

 

[brian]

Technically, you need to factor in the cost of battery degradation per mile too, and that adds a lot to it.

 

[Fabulist]

Technically, you need to factor in the cost of battery degradation per mile too, and that adds a lot to it.

I thought this particular comparison was for fuel cost only. If we start factoring in service cost and the cost of components wearing out (12 V Battery, Transmission, Tires, Filters, etc.) we are going to end up with an entirely different calculus but to be fair it should be the same on both sides of the comparison. They are both valid comparisons, but we should be comparing apples to apples either way.

-- Fab.

 

[brian]

Well, the battery is a consumable item that is directly related to miles driven, so I think it is relevant. The battery isn't like other normal components that wear out. Since we know that the battery has a life of 100,000 miles then you need to divide the cost of replacing it by 100k to get a battery-cost-per mile additional cost. Granted, most of us will have traded the car in before 100k miles, but still..,

 

[kabalah70]

I think dennis started the post to talk about fuel cost per mile, not total cost of ownership per mile. Otherwise we would have ot factor in engine degredation as well as it is directly related to miles driven too. I agree with Fab, that just fuel and electric cost is the easiest and provides a valid comparison.

 

[Fabulist]

Well, the battery is a consumable item that is directly related to miles driven, so I think it is relevant. The battery isn't like other normal components that wear out. Since we know that the battery has a life of 100,000 miles then you need to divide the cost of replacing it by 100k to get a battery-cost-per mile additional cost. Granted, most of us will have traded the car in before 100k miles, but still..,

As I understand it, the battery does not stop working at 100K miles. That's when it drops to 85% of capacity. You can continue to drive on that battery, albeit with a shorter EV range, which means you could run the ICE more often and burn more gas. The same thing happens in internal combustion cars where the engine output drops off over time and you have to work the engine harder for the same level of performance and you end up using more gas, but you generally don't run out and put a new engine in the car if your BHP and Torque output drop to 85% of a new engine.

So getting to my point (finally, right?) the only "consumable" part of the battery is the 15% that is lost through the charge/discharge cycles and that's what should be accounted for in the per-mile cost, not the cost of replacing the entire battery. Alternatively, you can also estimate how much more gas you will be burning as a result of having a shorter EV range and add that to the per-mile cost. But, IMHO, adding the entire cost of a battery to the 100K driving cost distorts the comparison in favor of the ICE.

-- Fab.

 

[dennis]

In pure electric mode, wouldn't you see closer to $0.13 per mile (20.1kWh x $0.20 / 32 miles) or as little as $0.08 per mile (assuming 50 mile range)?

It is not running the battery all the way down, so the full charge is more like 17-18 kwh for 30-35 miles. Using 32 miles, that works out to about $.11/mile in pure electric mode.

I also don't get 20mpg on the ICE going 80 mph on the freeway, probably more like 16, which works out to $.25/mile. So the "blended" cost ends up at $.18. Coincidentally the $ spent on gasoline and electricity were almost equal with my particular driving pattern.

 

[SoCalGuy]

In pure electric mode, wouldn't you see closer to $0.13 per mile (20.1kWh x $0.20 / 32 miles) or as little as $0.08 per mile (assuming 50 mile range)?

It is not running the battery all the way down, so the full charge is more like 17-18 kwh for 30-35 miles. Using 32 miles, that works out to about $.11/mile in pure electric mode.

I also don't get 20mpg on the ICE going 80 mph on the freeway, probably more like 16, which works out to $.25/mile. So the "blended" cost ends up at $.18. Coincidentally the $ spent on gasoline and electricity were almost equal with my particular driving pattern.

Interesting... with most of my freeway driving (around 75-80mph), I get around 20 or 21mpg.

 

[dennis]

Interesting... with most of my freeway driving (around 75-80mph), I get around 20 or 21mpg.

Is that with the battery at zero?

I will reset one of the trip meters next time battery is zero and see what the reported mpg is with ICE only. I haven't done that yet, so my 16 mpg was estimated based on how much fuel I used yesterday driving 110 miles with both battery and ICE.

 

[SoCalGuy]

Interesting... with most of my freeway driving (around 75-80mph), I get around 20 or 21mpg.

Is that with the battery at zero?

I will reset one of the trip meters next time battery is zero and see what the reported mpg is with ICE only. I haven't done that yet, so my 16 mpg was estimated based on how much fuel I used yesterday driving 110 miles with both battery and ICE.

That's with battery somewhere in the single digits, like 8 miles range or so. Similar results when battery was in the teens too.