170? 230? What do all these numbers mean?

You may have seen the recent headlines:

• Dakota County students say hybrid gets 170 mpg
• G.M. Puts Electric Car’s City Mileage in Triple Digits

Everyone is excited about high-mileage plug-in hybrids (GM has run a long, mysterious advertising campaign touting the 230 mpg figure). That's all well and good, but, really, is there a good way to measure energy use in miles per gallon when a fair amount of the energy in these cars is measured in miles but not in gallons? HOURCAR's own plug-in hybrids (oh, yes, we're way ahead of the curve; we got our first back in '06) are advertised as 100+ mpg and, under the right circumstances, achieve that. Sometimes. So, should we take all these new numbers with a grain of salt?

Yes.

As this page has discussed before, mileage estimates are just that: estimates. They are very variable. And the higher the mileage, the more variability will occur. Especially since the EPA has not yet finalized how they are going to measure PHEVs. GM's own Volt site has the disclaimer that

230 MPG and 25 kWh per 100 miles driven represents a preliminary GM est. of the final approved city rating; actual MPG and electricity consumption will vary based on many factors including driving habits, weather and road conditions and operation of electrical systems in the vehicle.

That's a pretty big group of ifs! It depends on the final rating, the actual consumption and many additional factors. Maybe 230 is a best-case scenario. Maybe not. But there's really no way to know.

The news articles, when you read past the lede, are not much more forgiving. The Times says:

The rating number, based on methodology drafted by the Environmental Protection Agency, is somewhat abstract, one auto specialist said, given that much of the city driving of electric vehicles will rely solely on the battery charge.

…

Figures for highway driving and combined city and highway use have not been completed for the Volt, but G.M.’s chief executive, Fritz Henderson, told reporters and analysts at a briefing on Tuesday that the car was expected to get more than 100 miles a gallon in combined city and highway driving.

100 mpg is slightly less than 230, and these numbers are coming from the same folks who, a few short years ago, thought the Hummer was the future of American motoring.

CNN goes to point out that this number has not been vetted:

The Environmental Protection Agency … says it has not tested a Chevy Volt and therefore cannot confirm the fuel economy values claimed by GM.

It goes on to point out that

Fuel economy for hybrid vehicles like the Toyota Prius is displayed in the same way as it is for any other gasoline-powered vehicle. It gets 46 mpg, for example, versus 19 mpg for a V-6 Ford Mustang.

That standard works because all the energy used by the Prius ultimately comes from burning gasoline. The Prius just uses that energy more efficiently than other cars do. The Chevrolet Volt, on other hand, runs on electricity that comes from two sources -- a battery as well as a gasoline engine.

When gasoline is providing the power, the Volt might get as much as 50 mpg. But that mpg figure would not take into account that the car has already gone 40 miles with no gas at all. So let's say the car is driven 50 miles in a day. For the first 40 miles, no gas is used and during the last 10 miles, 0.2 gallons are used. That's the equivalent of 250 miles per gallon. But, if the driver continues on to 80 miles, total fuel economy would drop to about 100 mpg. And if the driver goes 300 miles, the fuel economy would be just 62.5 mpg.

And there is, of course, the question of where all that electricity comes from. If it's from wind and solar, huzzah, it's clean. If it's from coal, as much of our energy is, it's not so clear-cut. Plus, how will a Volt measure up against the upcoming all-electric Nissan Leaf and rumored Prius Hybrid from Toyota? And how do you measure the efficiency—and pollution—put out by an all-electric vehicle?

Dave Friedman, quoted in the San Francisco Chronicle, may sum it up best saying that

Your mileage may vary means more to the owner of a plug-in than any other car on the market.

He also points out that conventional hybrids, paired with better engines and transmissions, will have more of an effect in the short term.

So, what does all of this mean? Well, there are couple of takeaways. The first is that while the future is closer, it certainly isn't here, and any numbers you see you should treat with a healthy level of skepticism (as well as a similar level of excitement). The second is that as we increase overall efficiency, how you drive will have more and more of an effect on efficiency.

Finally, as always, the best way to reduce your carbon footprint is to drive less. The marginal increase in emissions by taking the bus or train is almost zero, since they are running anyway. The marginal increase in emissions of walking or biking is negligible. In other words, it's great if your car gets 100 mpg, but your bike does a heck of a lot better than that.

HOURCAR's 4th annual member survey

Last week, HOURCAR turned four. In late June of 2005, HOURCAR launched with half a dozen cars, a couple dozen members and some hopes and dreams. Every year since, we've surveyed our members to find out, well, all sorts of information. We like to find out if anyone has given up their cars, if people bike and walk more (or less) and what our members think we could do better.

First of all, thank you to everyone who participated. We had over 300 survey responses (and congrats to Nadya, Becky, Rosalyn and Stephanie for winning the four $100 driving credits we drew as thanks for completing the survey), not a bad turnout.

Now to some of the nitty-gritty. Is HOURCAR getting cars off the road? Yup. More than half of our respondents were car-free before HOURCAR and intend to stay that way, and another 25% have either sold their car since joining or decided not to acquire an additional car.

We also asked people to estimate how many miles they drive per year (overall, not just in an HOURCAR) versus the amount they drove before joining. Now, this is somewhat sketchy because these are self-reported estimates, but of the 188 respondents (less than a quarter of the membership), the aggregate savings (including those who drove more) were 370,000 miles per year, more than are put on the entire HOURCAR fleet.

Then there's walking and biking. (HOURCAR loves walking and biking.) One third of HOURCAR members report that, since joining HOURCAR, they walk and bike more, only a few (fewer than five percent) report walking and biking less. And how often are HOURCAR members hitting the pavement? Well, 58% of members say they walk somewhere daily, and 83% report walking for transportation at least twice a week. 29% bike daily, and more than half bike at least twice weekly. 58% of HOURCAR members ride transit at least twice a week, more than half of those ride daily. Plus, most of our members use transit frequently to get around.

And then there's the use of a personal vehicle. When we asked how often our members drove one, 65% chose "never."

Check back soon for some fun anecdotes our members sent in!

What's your Walkscore?

According to the website Walkscore.com, ours is 98. Well, for two of our cars, anyway. #6 and #10 score 98 out of a possible 100. The rest of the HOURCAR fleet range as low as 66.

The average for the whole fleet is 87, meaning that we are "very walkable" and close to a "walker's paradise" overall. Of course, the site has its limitations: directions are as the crow flies and it sometimes misses certain stores in categories (like, you know, the Wedge and Mississippi Market Coops in "grocery stores").

They recently ranked the 40 largest cities (*) in the country (since Minneapolis and Saint Paul are separate, neither made the cut; an oversight on Walkscore's part) and the winner was San Francisco, which scores an eminently walkable 86, followed by New York, Boston and Chicago. (They have some pretty nice maps, too.) So, does that mean that HOURCAR is more walkable than San Francisco? Discuss.

(*) Why they did this I do not know. More pertinent would have been the central cities of the 40 largest metro areas in the country. But their methodology is their methodology (and, hey, it says almost nothing about access to jobs, which is probably the most important aspect of a location); perhaps it would make sense to contact them and tell them to please rank the Twin Cities, if only because we'd find it interesting.

Keep an ear out

It's getting to be that time of year again. The sun is out later, the snow is melting (at least it is melting more quickly) and when you go out for more than five minutes you can still feel your fingers and toes. Soon, more and more of us will hit the streets, on bikes without studded tires and shoes which stay dry for more than a block.

It's great to see spring springing, and I more than anyone am excited about biking in to HOURCAR HQ every day, but it's time to remember that not only are we more likely to be distracted when driving by a phone or an iPod (phones in the car are legal, headphones are not, for what it's worth), but that it applies to walking too.

NPR had a piece a couple weeks ago about this. It turns out that we use more than one of our senses when walking or cycling. Having earbuds in blocks out a lot of other sound, like the bus approaching or the light rail train coming down the tracks or the hybrid HOURCAR coasting to a stop for a pedestrian (I'll assume). So go out, and enjoy the fresh air, and bring your music. It's probably fine if you are walking around Isles, but think twice about blasting your tunes if you are crossing a lot of busy streets.

(Am I a hypocrite? Well, yes, a couple days back I listened to my iPod walking from the 63 bus up to our office. There was only one main street, but I'll think twice going forward.)

Walkers and bikers are fitter

A story titled "Leaner nations bike, walk, use mass transit" crossed our desk last month. We looked at the data for Latvia, Sweden and the Netherlands, where at least 50% of commuters walk, bike or take transit to work, and where obesity rates are half of what they are in the U.S., or lower. This got me wondering: how does the nation of HOURCAR compare?

Digging in to our annual survey results from last summer, we seem to do rather well. First of all, HOURCAR members tend to use non-driving (and healthier) transportation options more after they join HOURCAR. According to our survey, after joining HOURCAR:
* 28% of our members bike more,
* 33% walk more, and
* 31% take transit more,
compared with
* 3% biking less,
* 1% walking less and
* 10% taking transit less.

Overall,
* 66% of HOURCAR members walk daily (5 to 7 days per week), and 20% more walk 2-4 days per week.
* 25% of HOURCAR members bike daily, and another quarter bike at least two days a week, and
* 33% of HOURCAR members use transit every day, while another third take transit twice a week or more.
And, bucking the trend of America's car culture, 60% of HOURCAR members report they never use a personal automobile. In other words, HOURCAR members are on par, as far as using non-automotive transportation goes, with some of the healthiest countries around! So not only is HOURCAR good for the health of the environment, but it's good for the health of its members.