ASK THE EXPERTS: Judging Transportation

A plug-in hybrid electric vehicle.
This Toyota Prius was converted to a plug-in hybrid electric vehicle by
A plug-in hybrid electric vehicle.

I will buy a new vehicle in the next year, and I’m trying to sort through the hype. Can you give me some guidance on how to evaluate passenger cars for their environmental impact? I know that some hybrids are more fuel-efficient than others. And I know that some diesels get very high fuel economy. Then there are electric vehicles. What criteria should be used to make an intelligent environmental transportation decision? Fuel economy? Cost? Carbon footprint? I hope you can give me a sensible approach to this decision.

James Randelli • Charlotte, North Carolina

If you rack up lots of miles each year, then fuel efficiency should be a high priority. In this case, your best option would be a pure electric vehicle (if its range can meet your needs), but none are currently available from major manufacturers. Next best would be a plug-in hybrid electric vehicle (PHEV), which makes a very significant difference in fuel consumption by shifting part of your driving to a different energy source: electricity. If you have a clean electricity source, such as solar, wind, or hydro, that’s even better from an environmental standpoint. PHEVs are expected to hit the mainstream market in the near future. After that, a regular hybrid, which gets all of its energy from gasoline, since the gas engine charges the batteries, is a good choice. The hybrid takes advantage of the higher efficiency of the electric motor to improve fuel economy. If there is a comparable gas-engine version of the same vehicle, you can compare how much the mileage increases with the hybrid system. Beware, though: A so-called “mild hybrid” doesn’t do much more than paste a green label on a standard vehicle.

Another avenue for more eco-friendly transportation would be to buy a diesel vehicle with the intention of operating it on biodiesel or straight/waste veggie oil (SVO/WVO). This requires a little more commitment on your part. For SVO operation, you need to install a special kit in the vehicle. For biodiesel, you need to locate a source of fuel or make your own. Both SVO and biodiesel face some regulatory hurdles, so you should check out the situation in your area before committing to this option. Caution is in order, though: Because of California’s clean air regulations, most of the diesel passenger cars being imported to the United States do not achieve the good fuel economy of similar, but older models.

If you drive infrequently, other considerations will carry some weight. I would select a few high-fuel-efficiency vehicles that interest you, then check the manufacturers’ Web sites to see what they say about clean manufacturing processes and manufacturing for recyclability. If the vehicle is being built in a new factory, it will almost certainly be built with cleaner processes, and the factory itself will be more efficient in its use of energy. In addition, there are new types of paint that are less toxic, and manufacturers are starting to build with more materials that can be recycled at the end of the vehicle’s useful life.

From an emissions standpoint, a pure EV powered by RE produced at your home base, or an SVO vehicle would be cleanest. A plug-in hybrid would be a close second if your battery pack alone can get you most places you need to go. Conventional hybrids and biodiesel-fueled vehicles would be next. They both cover a broad range of emissions, depending on how much of the load is carried by the clean portions of the systems (batteries in the hybrid, bio in the biodiesel).

In all cases, the vehicle you choose should be small and, if non-electric, have a small engine. The bigger the vehicle, the more fuel it will consume. Small engines are “good enough” and appropriate for anyone serious about fuel economy.

Other options include a neighborhood electric vehicle (NEV), electric scooter, or bicycle, saving the car only for trips that really require it. Maybe joining a car-sharing service would meet some of your needs.

You’re right: there are a lot of variables, and there is no one best answer for everyone. The good news is there are several options for creative solutions tailored to your needs.

Shari Prange • Transportation Editor

Comments (2)

Jim and Elaine Stack's picture

Some things are worth more than money. Clean air, no imported fuel. These have values greater than money.

A bicycle is the most efficient vehicle in the world. Rain or snow use a velomobile like Organic Transport is making, it even has electric assist.

J Sandidge's picture

Mr Randelli. Myself, I would purchase a Ford Focus or a Toyota Yaris. Lifecycle price, carbon footprint, and total environmental impact over the 10 - 15 year life span possible with these vehicles with very, very little maintenance required (batteries at 100K miles on electric hybrids) coupled with driving slower and more reasonable than the average person would net you a better outcome than practically any other alternative and do this for a reasonable price. If you are looking at carbon footprint, and think the price of gasoline will go to $6/gallon permanently, buy a Prius. Oh, and in your area, if you use a plug in hybrid, just remember that your majority producer of electricity is going to be a coal fired power plant.

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