The Toyota family of Prius is growing again with the addition of a smaller, lower priced — and we think better looking — Prius than the original. The “C” stands for “city” and becomes the fourth hybrid to wear the Prius name, produced between the original, larger V last year and the soon-to-arrive plug-in model.

Prius debuted back in 1997 when oil was about $20 a barrel. Since then, more than 3 million have been sold worldwide, with more than 1 million in the U.S. alone. According to Rick Lo Faso, the corporate manager of car marketing for Toyota Motor Corporation, 96 percent of all Priuses sold in the last 10 years are still on the road, and nearly half of all hybrids sold today wear the Prius badge. Lo Faso says Prius will be the top-selling Toyota model by the end of the decade.

The Prius C is built on a modified five-door Yaris chassis and uses a smaller engine and battery pack than the standard size Prius liftback. The powerplant combines a 1.5-liter 4-cylinder running on the Atkinson cycle, an electric motor, a nickel-metal-hydride battery pack, and a continuously variable transaxle. The combined system totals 99 horsepower, 35 fewer than the larger Prius.

Toyota’s Hybrid Synergy Drive — used on all Prius models — has proven to be exceptionally reliable, and the nickel-metal hybrid battery packs, which are completely recyclable, have lasted well beyond even the most optimistic estimates. On the C, the battery pack is 24 pounds lighter, the entire hybrid system is 14 percent lighter, and the frame is a full 20 inches shorter and nearly 550 pounds lighter than the standard Pruis liftback.

Despite its diminutive size and weight, the Prius C scores an identical 50 mpg combined fuel efficiency rating, registering 53 mpg city (two better than the original Prius) and 46 mpg highway (two fewer than the standard model). By comparison, the C’s nearest competitor, the Honda Insight, scores just 42 mpg combined.

The Prius C will be offered in four trim levels, starting with the pretty well equipped C One at the sub-$20,000 price of $19,710, including the destination charge. Standard equipment on the One includes power windows and door locks, a USB port, Bluetooth, hill start assist, 15-inch wheels, a four-speaker stereo, and steering-wheel-mounted audio, climate, and phone controls.

Toyota execs expect that the Two and Three trim levels will account for 80 percent of total Prius C sales. Along with One’s standard equipment, the Prius C Two ($20,660) adds a six-speaker stereo, six-way power driver’s seat, 60/40 split folding rear seat, cruise control, tilt/telescoping steering wheel and a center armrest. With optional 15-inch allow wheels and power moonroof, the Prius C Three ($22,395) adds navigation and Toyota’s Entune audio system, body-colored door handles, a Touch Tracer display, push-button start, and keyless entry system.

The Prius C Four ($23,990) adds 15-inch alloy wheels, heated SofTex (ecologically friendly synthetic leather) front seats, fog lamps, and body-colored mirrors with integrated turn signals. Options on the Four include 16-inch alloy wheels with an upgraded suspension and a moonroof.

In all trim levels, there is too much hard plastic with too many grains and patterns. The steering wheel is the same as in the regular Prius, but the shift lever is the traditional PRNDL as opposed to the clunky joystick shifter found in other Prius vehicles.

During our drive, we found that the seats were unexpectedly comfortable and well bolstered, however, the cloth fabric on the base One model looked and felt cheap. At 6 feet, 6 inches, I found the front driver’s seat not only comfortable, but also surprisingly spacious with ample leg, hip, and shoulder room. But because I had the seat adjusted as far back as it could go, it would be impossible for someone to occupy the space in the rear seat directly behind me.

Climbing into the back seat, I realized that I couldn’t fit due to my height. Though the rear seatbacks angle more than they do in most vehicles, allowing passengers’ heads to fit better under the sloping roofliner above the cargo area.

All trim levels get a hybrid trip computer that displays information on a 3.5-inch screen in the center of the instrument panel. Along with standard trip information, the computer displays a graphic to show whether you are driving in all-electric or gasoline mode, if it’s recharging the battery, and a “score” on a scale of 1 to 100 measuring your driving efficiency.

There’s also a feature that allows the driver to input both the current price of gasoline and the mileage of another car to show the Prius C’s savings. This can be displayed for an individual trip or savings over a period of weeks, months, or even years.

What it doesn’t measure is the $5,000 extra cost one has to dole out for a hybrid, compared to the cost of a similar car with a standard gasoline-powered drivetrain. Most of these, including excellent non-hybrid vehicles such as the Ford Fiesta, Chevrolet Sonic, and Hyundai Accent, are now achieving 40 mpg. So, it would take about eight years, putting 15,000 miles per year, with a gas price of $4 per gallon to make up the cost difference between the C and a Ford Fiesta. And, the lower the cost of gas, the longer the payback time.

Still, for green car enthusiasts, the Prius C is a good buy, with 50-plus mpg for around $20,000.

So how does it drive? I had the opportunity to drive the One, Two, and Four models, and as expected, it was about as uninspiring as one could imagine. Toyota says the C can reach 60 mph in 11.5 seconds, but it seemed quicker than that when merging onto the highway. The ride was choppy and a bit noisy, and the brakes felt inconsistent — spongy at times, gripping at others.

I didn’t try to hypermile the fuel economy and drove it as I would any vehicle on a variety of routes: through residential streets, on hilly county roads, and at highway speeds. Our routes were between 12 and 25 miles each, and the best mileage we recorded was 56.2 mpg, the worst 47.2.

EV mode runs the Prius C on battery power only, operating at below 25 mph for a maximum of about 2 miles. There’s also an Eco button that further improves mileage while mitigating pedal throttle, climate controls, and overall efficiency.

Though, still puzzling is why the smaller, lighter Prius C, with a significantly smaller engine and drivetrain, gets virtually the same fuel economy as the larger and heavier original Prius.

The Prius C comes standard with nine airbags. In addition to front and side-impact airbags for the front seats and curtains for the front and rear occupants, there’s a driver’s knee airbag and two seat-cushion airbags for the driver and front passenger. While these airbags don’t directly protect occupants, they inflate to better position the driver and passenger in relation to the other airbags in the car in the event of a crash.

Neither the National Highway Transportation Safety Administration nor the Insurance Institute for Highway Safety has crash-tested the Prius C as of this writing.

Prius already boasts the highest owner loyalty of any vehicle on the market, with 96 percent of owners saying they would buy another. And while it’s not for everybody, we expect the Prius C, a very good hybrid overall, will sell like crazy for those who are on a tight budget, enthusiastic about going green, and keep an eye on the ever-rising price of a gallon of gas.