Efficient Cars Chart for June, 2012

Spreadsheet

The spreadsheet shown here, refined and updated over five years, is our ongoing attempt to summarize the economic and carbon-footprint efficiency of cars you can buy now, or in the near future. Note that it includes a few sample used cars. The carbon generated in manufacturing any car usually exceeds the carbon emissions for the first year of driving ― and of course any new car loses value quickly within the first year. This means, over the short haul, that operating an efficient used car puts less carbon into the atmosphere than even buying and driving a more fuel-efficient new one.  Buying a fuel-efficient used car is often the more cost-effective way both to save money and to reduce the household’s carbon footprint.

How to read the chart:

Cars are arranged on the chart by motor type, and then in order of their estimated cost to buy and operate.

Curb weight reflects the car’s general heft, in pounds. It’s what the car weighs with a full tank of gas but no passengers or luggage. Of course, an electric car has no gas tank, and the batteries don’t grow lighter as they discharge. A lower curb weight almost always means a more efficient car.

MPG is miles per gallon, according to tests conducted by the Environmental Protection Agency (EPA). EPA gives mileage for city driving, highway driving and combined; we’ve shown the city and highway figures. If you do mostly stop-and-go driving – neighborhood errands, deliveries, or taxi-cab driving, for instance – the city number is more relevant. To convert MPG to kilometers per liter, multiply by 0.425. Note that the EPA gives a MPG (equivalent) figure for pure EVs. For plug-in hybrids (PHEVs), we provide an MPG (equivalent) for pure electric mode, and a second MPG figure for highway fuel efficiency.

Price is manufacturer’s suggested retail price in U.S. dollars for new cars and approximate retail market value for used cars. Prices do NOT include federal or state incentives for low-emission vehicles, so after-tax pricing for EVs and some hybrids may be significantly lower than shown here.

Seats is number of seats, according to the manufacturer. If you carpool or plan to transport whole soccer teams, this is an important number. You might feel better about carbon emissions if you calculate pounds of CO2 per passenger-mile. We’ve done it for you, and the column labeled “Average CO2 per mile direct lb/seat” makes the relatively heavy seven-passenger Toyota Highlander SUV look pretty good.

Drive categories include rear-wheel drive (RWD), front-wheel drive (FWD), full-time all-wheel drive (AWD) and on-demand four-wheel drive (4WD). 2/4WD means that the base-model mode is RWD or FWD but that 4WD is an available option.

HP combined is the combined horsepower of the piston engine and any electric drive motor.

Drive type is the technology of the prime mover. IC indicates a normally aspirated (non-turbo) internal combustion engine using gasoline, compressed natural gas or ethanol fuel. Tdiesel is a diesel engine with a turbocharger, able to run on diesel or biodiesel. Hybrid uses an IC engine assisted by an electric motor. PHEV is a plug-in hybrid, able to run an initial distance on battery power alone — for instance, a PHEV40 can run approximately 40 miles before the IC engine needs to charge the batteries. EV is a pure electric vehicle, and EV100 means it has the battery capacity to run approximately 100 miles on a charge.

Fuel types include gas, for cars that run on gasoline. Flex means the car is equipped to use either gasoline or an ethanol blend (but note that all modern gasoline cars can be cheaply modified to run on ethanol). D means diesel, and these cars can also run on biodiesel. CNG is compressed natural gas. Li represents any form of lithium-ion batteries, and NiMH is nickel-metal hydride batteries.

CO2 per mile direct is the approximate mass of carbon dioxide straight out the tailpipe, given in pounds. This is a very rough approximation, useful mainly for comparisons between cars. The figure will vary dramatically depending on driving conditions and the driver’s accelerating and braking habits.

E-mode carbon footprint 100% coal applies to EVs and PHEVs. It estimates the pounds of carbon emitted in charging the vehicle if your electric utility uses coal-burning generation exclusively. It’s given in pounds of CO2 per mile and assumes half of the miles driven are city and half are highway. Note that if this is the case, your EV may produce a bigger carbon footprint than some modern high-efficiency hybrids. This is a very rough approximation, useful mainly for comparisons between cars. The figure will vary dramatically depending on driving conditions and the driver’s accelerating and braking habits. Also, very few areas get 100 percent of their power from coal now.

E-mode carbon footprint 50% coal estimates the pounds of carbon emitted in charging an EV or PHEV if your electric utility uses coal-burning generation for half its delivered electric power and the other half from non-carbon emitting sources. California’s utilities, for instance, get less than 20 percent of their electric power from coal; nationwide, the average is about 40 percent. There is no column for carbon emissions where electricity is provided from carbon-free sources. In that situation, the total carbon emission is zero. Note that these carbon-footprint calculations are very rough guesstimates, useful only for comparison between cars. They don’t include the proportion of carbon emissions entailed in natural gas (significant in most states now) and fuel-oil generation (significant in Hawaii). To learn about the balance of fuel emissions in your area, see  eia.gov/environment/reports.cfm?t=9999&f=d, and the report eia.gov/FTPROOT/environment/e-supdoc.pdf.

KWh per mile is the electrical energy required to run the car one mile. This is a very approximate figure and should be used only to compare cars, not to calculate range.

Fuel cost per mile is the approximate cost of fuel, assuming that electricity for charging an EV costs 11 cents per kilowatt-hour, gasoline $4.00 per gallon, compressed natural gas $2.55 per gallon-equivalent (GGA) and diesel $4.15 per gallon. These were current prices in April 2012 when the chart was assembled.

10-year cost is the cost per mile to operate the vehicle, combining purchase cost and fuel costs at 12,000 miles per year at today’s prices. This figure does not include taxes, rebates, insurance or maintenance costs, which vary locally and over time. Note that maintenance costs should be lower for a pure electric vehicle, which needs no regular oil and filter changes, but that battery replacement may be an expensive item after eight or ten years.

Download the complete spreadsheet, and tailor it by adding your car or updated fuel prices: Click here.

http://ases.org/wp-content/uploads/2012/06/Cars12chart1.xls

About Seth Masia
Seth Masia is editor of SOLAR TODAY Magazine and director of communications at the American Solar Energy Society.
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