This is an archived article that was published on sltrib.com in 2017, and information in the article may be outdated. It is provided only for personal research purposes and may not be reprinted.

For 2017, Toyota has added its most fuel-efficient Prius ever: a plug-in gasoline-electric hybrid called Prius Prime that can travel up to 640 miles on a full electric charge and a single tank of fuel.

With its federal government fuel ratings of 54 miles per gallon on gasoline power and 133 mpg-equivalent on electricity plus gasoline, the new Prius Prime is the most fuel-efficient plug-in gasoline-electric hybrid sold in the U.S., topping the 2017 Chevrolet Volt with its 420-mile total range.

Prius Prime drivers can travel for about 25 miles on electric power only and at speeds up to 84 miles per hour.

A gas-thrifty, four-cylinder engine can propel the car the rest of the way, receiving supplemental electric power as the onboard lithium ion battery pack is replenished.

Drivers also can select when to travel on silent, all-electric power and when to let the car manage the power modes for efficiency.

It takes just over two hours to fully recharge the Prius Prime battery pack using an electric-car fast charger and 5.5 hours using a regular 120-volt, household outlet.

The 2017 Prius Prime has a starting manufacturer's suggested retail price of $27,985, which is $2,415 more than the starting retail price for a non-plug-in, 2017 Prius hybrid whose government-rated travel range is 588 miles.

But the Prius Prime starting price is $6,010 less than the starting MSRP, including destination charge, for the 2017 Volt, a plug-in, hybrid competitor.

That's before figuring in a federal government tax credit of $4,502 that's available for buyers of the Prius Prime. Purchasers of the Volt qualify for a $7,500 federal tax credit. The tax credits are one-time deductions from taxable income, not a direct decrease in the purchase price of the cars.

The Prius Prime is Toyota's latest effort to energize Prius sales, which declined 26 percent last year to 136,632.

Toyota sold a plug-in version of the Prius in the U.S. from the 2012 to 2015 model years. But it was not as fuel efficient as the Prime, had a travel range of 540 miles and was sold in a limited number of states.

The Prius Prime exterior styling is polarizing, with opinions ranging from funky to ugly.

It has only four seats, so front- and rear-seat passengers all have a middle armrest console.

The ride in the test top-of-the-line Prius Prime Advanced was quiet and comfortable.

Torque from the electric motor came on instantly and could squeal the front tires. The 1.8-liter, four-cylinder gas engine only generates 95 horsepower, but this is boosted to 121 with electric power.

The continuously variable transmission worked smoothly. The stub of a gearshift lever was gimmicky and awkward, however.

Passengers didn't feel a lot of harsh impacts. The upgrade from solid rear axle to a double wishbone suspension in the rear is noticeable.

The electric power steering was impressively accurate and natural feeling.

Brakes supplied good stopping power, and the stacked, two-window design out the back hatchback lid allowed for decent views of traffic behind the car. A rear camera is standard and operated when the car was in reverse gear.

The interior of the test car was reminiscent of the Volt, with futuristic-looking white plastic generously applied to the dashboard.

As in other Priuses, there were no gauges directly in front of the driver. They were clustered just below the windshield in the middle of the car and offered an array of information, including a list showing average fuel economy for each day's driving and scores for eco driving.

The test Prius provided even more information in its tablet-sized, high-definition information and entertainment display in the middle of the dashboard.

The navigation maps, for example, were large, colorful and easy to read. And, the display could be swiped and pinched, to change screen views.

Buyers can pack the Prius Prime with Toyota's latest safety and technology features, including park assist, blind spot monitor and stolen vehicle locator. But they add to the price, which can top $36,000.