2013 Tesla Model S [photo: David Noland]Enlarge Photo
With these new numbers, he recalculates the Tesla's total effective carbon emissions to be 346 g/mi, not a lot more than the 292 g/mi I calculated above.
Weiss also downgrades his SUV bogeyman, pointing out that even at his revised lower figure of 346 g/mi, the Model S is still a worse carbon polluter than the Toyota Highlander, which the EPA rates at 312 g/mi.
What about carbon from gasoline production?
But for all his zeal in exhaustively parsing the carbon footprint of electricity production, Weiss conveniently forgets to mention that producing gasoline also has its own carbon footprint.
According to a 2000 report from the MIT Energy Lab, gasoline production accounts for 19 percent of the total lifetime CO2 emissions of a typical car. Actually driving the car accounts for about 75 percent of its lifetime carbon output.
Thus the carbon footprint of fuel production adds about 25 percent to a gas car's nominal CO2 emissions number.
Sorry, Mr. Weiss. If you apply the same rules to gasoline cars that you did to the Tesla, your Toyota Highlander just went from 312 g/mi to 390 g/mi.
On this adjusted apples-to-apples basis, the Tesla figure of 292 g/mi is roughly comparable to that of the Scion iQ.
With all the growing concern about global warming and carbon emissions, old-fashioned "smog" air pollution--primarily nitrogen oxides (NOx) and sulfur dioxide (SO2)--has receded into the background.
Due to strict emissions laws, modern gasoline cars emit very little of these lung-threatening pollutants. The same cannot be said, unfortunately, about coal-fired powerplants.
Weiss calculates that powerplant emissions give the Model S an effective level of NOx pollution about triple that of the EPA limit for gas cars. (I'm discounting his suspect inclusion of vampire losses.)
The situation for sulfur dioxide is much worse. Weiss calculates that effective Model S sulfur dioxide emissions equal that of about 400 gas cars. (Again, the suspect vampire data is discounted.)
Weiss writes, "In many states, including California, if a smog-testing center could measure the effective emissions of a Tesla Model S through a tailpipe, the owner would face fines, penalties, or the sale of the vehicle under state 'clunker buyback' programs."
In terms of sulfur dioxide, gas cars are so clean and coal-fired electricity so dirty that a 60-watt light bulb effectively emits as much sulfur dioxide as an average gasoline car driving at 60 mph.
Frankly, I can't argue with these disturbing numbers, and I have not seen them refuted anywhere. But they say more about the tough emission laws for gas cars and the remarkably lax rules for coal-fired powerplants belching sulfur dioxide than they do about the Model S.
Nevertheless, I'm feeling a bit guilty about the sulfur dioxide spewing out of my Tesla's virtual tailpipe.
At least I live in New York state, which uses coal for only about 10 percent of its power production. That's about one quarter of the U.S nationwide percentage, so presumably I'm "only" 100 times worse than a gas car when it comes to sulfur dioxide emissions.
Fortunately, I'm not alone; the vast majority of electric cars operate in states with low-coal grids like California, Washington, and New York.
And the grid is slowly getting cleaner. As more wind, solar, and natural gas come online and antiquated coal plants are shut down, my effective SO2 emissions will steadily decline.
So in the end...
After all of this, the conclusion seemed clear: I drive a kick-ass, high-performance, five-seat all-electric luxury sport sedan that has the same wells-to-wheels carbon emissions as a tiny Scion minicar with two real seats.
Anybody got a problem with that?
When it comes to virtual tailpipe emissions, carbon and otherwise, the Model S ain't perfect.
But if you ask me, it's a huge step in the right direction.
David Noland is a Tesla Model S owner and freelance writer who lives north of New York City.