| For mileage range | 0 to 36k | 36k to 60k | 60k to 100k | 100k to 150k | greater then 150k |
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Basic
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Gas costs
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kwh costs
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Enviro
costs |
The environmental costs of manufacturing a car can be approximated by the energy (btus) needed per-pound. You can change these BTU values, which will change the
gallons per lb ... variables
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Use
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Car 1:
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Car 2:
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Car 3:
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Maintenance
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Summary tables
Basic parameters (same for all cars):
Time span: years
Short trip miles:
Long trip miles:
Discount rate:
Full gas price:
Full KWH price:
What is a collection of cars
Instead of choosing between different cars, it might be more fruitful to compare sets of cars. For example, two reasonable choices might be:
When you define a collection you must specify what fraction of your short trips, and what fraction of your long trips, you will allocate to each car. This fraction is used to compute costs (such as yearly gas costs). Note that the computation is simple, it just takes the fraction times the car specific costs (a more sophisticated allocation could differentiate different types of short trips to different cars).
The full gas price
The full gas price includes both the price at the pump, and the environmental costs (on a per gallon basis). These environmental costs can include global warming (CO2) costs,
air pollution costs, and resource depletion costs.
The full electricity price
The full price per kwh includes both the price from the utility, and the environmental costs (on a per kilowatt hour basis).
These environmental costs can include global warming (CO2) costs, air pollution costs, and resource depletion costs.
Computing the full electricity price
The full electricity price is a
weighted average of the cost of the electricity from the utility (including environmental costs),
and the cost of the electricity from green sources (such as rooftop photovoltaic panels).
What if I have solar panels, or other green energy??
Solar panels, windmills, and other green energy have very low costs, both in terms of retail and environmental.
If you are producing green energy, should you adjust your kwh costs accordingly? Alas, in almost all cases, the economic's answer is no. Why? The extra electricity used to power an electric car is being purchased from somewhere, with all the attendant costs (including environmental). If you didn't use an electric car, this energy would not have been produced.
In other words, it is marginal consumption, so should be priced at the marginal rate -- which (unless you are producing an excess amount of energy that is being wasted)
is from the utility.
The yearly fuel costs to run this car
The yearly fuel costs are computed using the gallons consumed on short (city) trips and long (highway) trips in this new car. And, if this is an electric
(pluggable hybrid and all-electric) car, the electricity used.
The average mpg is across both short and long trips (it does not include trips under electric power).
The cost per ton of CO2
One strategy for adresssing climate change is tax CO2 emissions. Typically, this would be done by taxing the fuel (rather than directly measuring emissions).
For example, some analysis suggests that a $50/ton-of-CO2 might lead to a stabilization of CO2 levels. In addition to choosing a tax per ton, you can modify the pounds of CO2 per gallon of gas, or per kwh.
The EV range
How far can this car be driven in battery mode.
stMiles EV: short trip miles under battery power
The short workday and weekend daily short trip miles, and the distribution of short trips, are used when you have a partial electric car.
They are used to compute the fraction of miles powered by electricity, and the fraction powered by gasoline.
It is used to calculate costs: the higher the fraction, the more the car is using electricity hence the less it is using gas. These values are compared to the EV range: the longer the EV range, or the shorter the average daily mileage, the more miles are under electric poser.
Miles per kilowatt hour.
How many miles can the car go on one kilowatt hour of charge (in battery only mode)?
Note: if you don't have that number handy, the storage capacity of the battery in kilowatter hours (kwh) can be used... |
Basic specs on this car.
The car you are evaluating can be new, used, or one you already own.
For certain kinds of cars, some of the fields should be set to 0
Is this car a hybrid? Is this car electric?
Chose which kind of car this is.
Is this car a hybrid? Is this car electric?
Check these buttons if the car is a hybrid, or if the car has electric (plug in) capabilities.
Environmental fuel costs
The several categories of environmental fuel costs should contain guesses as to the "non-market" costs of using energy resources.
This includes co2, other air pollution, and resource depletion (i.e.; costs of maintaining military)
Environmental costs of building a car
When a car is built, energy is used. The environmental costs of this energy should be accounted for.
A simple way of doing this is to assume that it takes a constant amount of fuel (gas) to create a pound of car. In fact, given the material of electric/hybrid cars, it may take more fuel to build a pound of hybrid car.
You can use the
Environmental costs of building a car
The values in this worksheet are use to estimate the gallons of gas to build a car. More precisely, the full car cost table uses
an estimate of the energy required to build a car. This estimate is converted to gallons of gas, and the environmental costs of this quantity of
gasoline is used as the environmental costs of building a car.
To do this, a btu per pound of car value is used. Two values should be specified: one for normal cars, and one for hybrid cars. Default values, that are derived from averages across all cars, are provided. Note that this is used for all cars, all that matters is whether the car is a hybrid or not (and the weight of the car). By the way, electric cars will have similar features as hybrids (large batteries). Notes:
Maintenance costs
Maintenance costs means all yearly costs that are not fuel costs. Actually, what is of greatest interest are the costs that are not constant across
cars. Thus, registration fees and liability insurance can be ignored. Examples of interesting costs are repair costs and equipment insurance, since these
can vary across cars (especially across cars with different mileage).
For example: older cars require more repair dollars, but less equipment insurance.
A value for each year (up to the years specified in the time horizion variable) should be specified. You can auto fill these values. Auto fill uses the maintenance cost variables (in the useage data section). These are combined with the yearly predicted mileage of the car (based on starting mileages and the miles driven per year) to compute maintenance & insurance costs.
Insurance and repair variables
The insurance and repair parameters used to compute maintenance costs. In particular, when you push a car's Estimate using mileage,
these paramters are used to compute yearly maintanece costs
These insurance and repair parameters do not vary across cars. Instead, they are combined with the expected mileage a car will have at the beginning of a year. You will fill in a range of values, that are for a range of miles. At the beginning of each year, the mileage for a car is computed, and then the matching range is found. The repair-costs-per-mile, and the insurance-for-year, for this range are then used. Note that the insurance costs are constant, while the repair costs depend on the miles driven per year. Typically, one expects the per mile repair costs to increase with mileage (since high mileage cars need more frequent main down more often). One might also expect insurance costs to drop (say, because you increase the deductible as the car ages). Notes:
MPG help.
Enter the miles per gallon: for both short (city traffic) and long (highway) trips.
You can then click the ... button to see your gasoline consumption and costs.
Trip fraction help
In addition to combining seperate cars, you can combine combinations of cars. In other words, you can compare the cost of purchasing a fancy new car,
versus purchasing a cheaper car and keeping your old one.
In order to combine costs, the fraction of useage of each car is needed. Two numbers are required: the fraction of short trip miles in this car, and the fraction of long trip miles. Note that the lt (long trip), and the st (short trip), fractions should add up to 1.0 (when summed across all cars in a collection).
Distribution of short trips
In order to determine what fraction of your short trips are under electric power, a distribution of short trip lengths is helpful.
The values here are used to approximate this distribution.
You should enter values relative to the average short trip miles you drive in a day. These are then applied to the workday and weekend average short trip miles per day (that you entered above). For example, if your average daily mileage is 50, but you drive anywhere between 33 and 66 miles, enter 33 in the 66%, 100%, and 133% boxes. Notes:
EV Miles
In order to determine how many KWH your electric car uses, a few variables are used:
Week and weekend days
You can use this worksheet to determine how many short-trip miles you drive, and approximate the range of mileage.
By short-trips, we mean mostly city traffic. In comparision, long-trips mean highway driving. As a convenience, two kinds of days can be specified: week days and weekend days. You can think of week days as work days, where a round trip commute is the bulk of your travel. Weekend days would then be non-work days, where the bulk of your driving is shopping, etc. However, you can divide these days in whatever fashion matches your driving habits. In fact, you can use just one category. If you do that, increase the number of days per year to 365 or so. Why do we bother? Hopefully it makes it a bit easier to compute your short trip distance. Perhaps more importantly, it facilitates accurate predictions of gas & electricity useage for pluggable hybrids. It helps predict how often you will run out of battery power and switch to the gas engine.
Creating a collection of cars
To specify a collection of cars, you must chose from amongst currently defined cars.
Miles
Maintenance costs for a collection of cars
The maintenance costs for a collection of cars is, by default, automatically computed using miles driven in a year and the starting mileages at the beginning of the year.
That is: if you entered your own year-by-year maintenance values for a collection's cars, the computed values (for this collection) may be out of sync. In this case (where you didn't use the Estimate using mileage buttons), you can create your own year-by-year maintenance values for a collection. Note that the car-by-car breakdown will display the automatically computed values. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| How many cars do you want to compare (2 to 4): | ||
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| What is the price of a gallon of gas: | $ | |
| What is the price of a kwh of electricity | $ | |
| What is the price of a ton of carbon | $ | |
| How many in-town miles do you drive per day (on average). | 7000 | |
| How many highway miles do you drive per year. |
| Car 1 |
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| Car name: | || |
| Basics: |
Weight:
Price:
18000
Current mileage:
Price (or book value):
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| Type of car: | || || || |
| Miles per gallon: | In-town MPG: Highway MPG: |
| Miles per kwh: | Electric range: || Miles per Kwh: |
| Car 2 |
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|---|---|
| Car name: | || |
| Basics: |
Weight:
Price:
18000
Current mileage:
Price (or book value):
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| Type of car: | || || || |
| Miles per gallon: | In-town MPG: Highway MPG: |
| Miles per kwh: | Electric range: || Miles per Kwh: |
| Car 3 |
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|---|---|
| Car name: | || |
| Basics: |
Weight:
Price:
18000
Current mileage:
Price (or book value):
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| Type of car: | || || || |
| Miles per gallon: | In-town MPG: Highway MPG: |
| Miles per kwh: | Electric range: || Miles per Kwh: |
| Car 4 |
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|---|---|
| Car name: | || |
| Basics: |
Weight:
Price:
18000
Current mileage:
Price (or book value):
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| Type of car: | || || || |
| Miles per gallon: | In-town MPG: Highway MPG: |
| Miles per kwh: | Electric range: || Miles per Kwh: |
| Details... |
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The easy entry method uses a number of default assumptions.
These include: |
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| Collections of cars | What if you want to compare collections of cars? It may be advantageous to have more than one car. For example, a small fuel-efficient car for in-town driving,
and an older car for the long trips. How would such a collection of cars compare to a single car, or to other collections.
For example, what's more cost effective:
a new and expensive partially electric car, or a cheaper all-electric car and your current clunker for the occassional long trip?
Specifying a collection is readily done -- but not if you use this EZ method.
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In other words, if you are willing to wade through the forms (they aren't that bad!), you can really unleash the power of this Calculate costs of car ownership application.