The Air We Breathe

R310b Sunday's Washington Post Commuter Page (Page 2 in the Metro section) had a nice discussion of air quality. I have not been able to find it online; evidently it is only in the print edition.

The most striking visual on the page was a graph that showed the comparative emissions across several types of vehicles. Here are the numbers from the table but without the visual impact of the chart:

Nitrogen Oxide Emissions in grams/mile:
Light-duty hybrid (Prius, Civic hybrid) 0.02
Passenger car (Camry, Accord, Malibu) 0.10
Light-duty truck 2 (Cherokee, Caravan, Sienna) 0.30
Light-duty truck 4 (F-150, Sequoia, Land Rover) 0.60
Heavy-duty truck (Hummer, RVs) 0.90

That means it would take 5 carpoolers in a regular passenger car before the emissions would be equal to 5 Priuses or 15 passengers in a minivan to equal 15 Civic hybrids. A big SUV emits 30 times as much ozone-causing pollution per mile than a hybrid! A Hummer 45 times as much!

This table makes it clear that increasing the fleet of hybrid vehicles in our area, particularly if they are replacing other vehicles, would make a big dent in our air quality problems. In fact, DC is doing well with hybrid ownership, double the national average (link). Much of this has been driven by the HOV exemption for clean vehicles, prompting some drivers to invest in hybrids in order to be able to drive on the HOV lanes. This year, also, Arlington County has introduced a tax break for people to buy hybrid vehicles.

These seem like good policies as we strive to improve regional air quality. There has been controversy about whether the clean-vehicle exemption for HOV should be terminated. I think this information supports the position to keep it in place, since 3 single-occupant Priuses only emit 60% or less emissions than a car (or worse, an SUV or minivan) with three passengers. Some parties believe the exemption should end, because too many single-occupant vehicles will clog the carpool lanes. I66I will only be convinced after much more aggressive efforts, including much higher fines, are taken to eliminate the HOV violators, who I see all the time on I-66.

Keep in mind that owners of these vehicles are contributing to better air quality with 100% of the miles they drive, even though only 15% - 50% of their driving might be on HOV lanes, so it is in the interest of all who want cleaner air to encourage more purchasing of cleaner cars.

(In the interest of disclosure, I own a Toyota Camry hybrid, but do not have the requisite license plates to drive in the HOV lanes. I also have a personal interest in improving air quality, because my daughter suffers from asthma.)

Our New Hybrid: An Update

Toyotacamryhybrid2007_2 Back in March I posted about our brand new 2007 hybrid Toyota Camry. It looks silver, but it is actually "titanium!" We've now driven it about 1800 miles, and I have a report.

It has some cool features. Probably the coolest is the "smart" key that allows you to unlock, start and drive the car without ever taking the key out of your pocket or purse. Once you start using a smart key, you'll wish you had one for your house, too. Also, the hands-free Bluetooth connection to your cell phone is a nice convenience and safety feature.

However, the most important feature, fuel economy, has been a big disappointment. We've averaged only about 31 miles per gallon--no better than lots of economy vehicles that are not hybrids. I still feel good that the air quality emissions are much better than the vast majority of vehicles--especially since the DC area has such poor air quality, but I've not been impressed with the mileage. Because the vehicle has regenerative braking and often shuts down instead of idling, it's supposed to be better in city driving, which is the vast majority of what we do. That has not been our experience. We did pretty well on our one road trip to Philadelphia. Our highway mileage was over 40 mpg, and our total trip including the city driving while we were there averaged about 36-37 mpg.

The Logo_gh_wreflect_3 web site keeps a database of fuel efficiency for the various hybrids. Our mileage is in the bottom 10% of the Camry hybrids reporting there (average is 37 mpg). So, why? I think it's because of the short trips that we take. For mosts trips of under 3 miles it is very difficult to get the car to average above 30 mpg for that trip (oh, yeah, another feature is that it tells you your fuel efficiency for every trip at the end of that trip). It doesn't do well for the first couple of miles. Probably 60% - 70% of our trips are shorter than 3 miles.

The good news is that shortly after we purchased it, Arlington County adopted a tax break for hybrid cars, so we'll save several hundred dollars on our personal property tax this year, which will more than make up for the difference in fuel economy that I had hoped for and what we are actually getting. It won't, however, make up for the greenhouse gas emissions I had hoped we would be reducing.