In his 1992 book, Earth in the Balance, Al Gore proclaimed the internal combustion engine “a mortal threat . . . more deadly than that of any military enemy.” You may or may not agree, but it’s hard to argue that limiting fossil fuel use isn’t a positive.

Modifying which car we drive and how we drive it are things we all can do. To reduce our gasoline consumption, we should be driving slowly and steadily, accelerating slowly, and walk or bicycle when feasible. And simple maintenance, like keeping the right tire pressure, increases efficiency. As for ‘green vehicles,’ these come in a variety of flavors, from microcars like the Smart car, to hybrids like the Prius, all-electrics like the Nissan Leaf, and high-mileage vehicles like the diesel VW Passat TDI. Let’s see how they stack up.

[subcompacts/microcars]
Smaller, lighter vehicles are intrinsically more fuel efficient. Their production is also less environment-destructive. Anyone who has traveled knows there are many very small cars that never make it to the States. At Plaza Mercedes-Benz, I test drove a Smart car and at Lou Fusz Fiat, I drove a Fiat 500.

Smart for two>> MPG 34 city/38 highway/36 combined | $13,270-$17,930 (convertible)
(+) Small enough to park two in a single spot. Iconically cute with practical interior.
(–) Uninspiring drive train, lackluster mileage. Some drivers may be intimidated in traffic by such a small vehicle.
(=) If you’re in love with it, buy it! If not, drive it and decide for yourself.

Fiat 500>> MPG 31 city/40 highway/34 combined | $16,195-$26,095 (Abarth turbo)
(+) Neat interior with a compact rear seat and good storage. Exceedingly cute! A great drive.
(–) Premium fuel. Turbo Abarth very speedy and sporty, but fuel mileage suffers a bit.
(=) You can find a more efficient car, but the Fiat 500 excels in smiles per gallon.

Mini Cooper>> MPG 30 city/42 highway/34 combined | $19,950-$47,353 (fully optioned John Cooper Works)
(+) The original retro-styled cute car, its powerful and great handling package has made it a favorite.
(–) Small for some, and can become pricey depending on options. Dodgy service history.
(=) Try it. Consider an informed purchase on the used market.

[hybrids]
If you examine energy use in a vehicle, a modest amount of power is needed to maintain constant speed on level ground. Much more power is needed intermittently to accelerate the vehicle to speed, and car brakes normally use friction to slow the vehicle, converting all that hard-won momentum into brake heat. A newer innovation such as the Chevy Volt is the ‘plug-in hybrid,’ a design that may allow electric vehicle (EV) operation over a limited range, with an internal combustion motor for backup.

Chevrolet Volt EV >> MPG 35 city/40 highway/37 combined | $34,185-$36,605
(+) A good drive! $7,500 federal tax credit in 2014
(–) Only 38 mile pure EV range; Engine noise in gas mode with premium fuel.
(=) Despite being stigmatized by issues at first, the Volt is a reasonable plug-in that operates well as an EV with gas for backup.

Toyota Prius >> MPG 51 city/48 highway/50 combined | $24,200-$34,720
(+) Well-sorted with great mileage. Practical and capable. Feel virtuous!
(–) Plug-in model only has an 11-mile EV range. Noisy and poor handling. Not a driver’s car.
(=) Drive it and decide if you like it. It’s a great car if you aren’t bothered by the shortcomings.

[electric vehicles (ev)]
You can ditch the internal combustion engine entirely and go all-electric. There remain significant impediments to the all-EV. (Long charge times, the need for special charging stations, and limited mileage range pose a challenge.) For most of us, these vehicles will be city cars at best. Also remember that most home electricity is produced through the burning of fossil fuel. With losses in transmission and charging, the ‘carbon footprint’ isn’t minimal unless you have your own hydroelectric generator.

Nissan Leaf>> MPG 126 city/101 highway | $21,490-$34,840
(+) Compact car feel and reasonable performance. Resembles a ‘normal’ car when driving.
(–) Rated 84 mile range. Charges in as little as four hours with special charging station, but a conventional
wall outlet takes 16 hours.
(=) A practical city car for the right person. Won’t work for long trips.

Tesla S>> MPG 94 city/97 highway/95 combined | $63,570-$119,720
(+) Capable luxury, high performance EV. Range up to 265 miles. St. Louis has a service center.
(–) Cost, small support network. Charging time.
(=) A fabulous vehicle, if you can afford it.