By Jim Meachen and Ted Biederman

Owners of a last-generation Toyota Prius hybrid who are ready to trade in their well-used model for an all-new Prius with its trendy styling, myriad of modern technology features, and its improved gas mileage can be justifiably mistaken if they think the Prius Prime is just a new luxury trim level available on the fourth-generation Prius that hit showrooms as a 2016 model.

Here's the skinny on the Prime — it's not a new trim level, but an all-new plug-in hybrid slightly larger and more fuel efficient for people who want all the amenities that Toyota can throw at them while delivering some of the best gas mileage available in a car that includes a gas engine.

In either configuration, the newest Prius is more refined, it handles and drives more like a normal sedan than the last-generation Prius and it delivers better gas mileage in combined city and highway driving. In-fact these cars are all about gas mileage — great gas mileage — measured by miles per gallon entirely in the 50s regardless of driving conditions.

In a nutshell:

• The Prime comes with a considerably larger lithium-ion battery that can be recharged on household current offering up to 25 miles of electric-only range — fully recharged on a 240-volt charger in just two hours or on a 120-volt household current in 5.5 hours.

• The Prime is 6.5-inches longer than the standard Prius to accommodate the larger battery pack and seats only four.

• The Prime is more fuel efficient than the standard Prius even without figuring in the extra miles derived from the electric motor with a combined mpg rating of 54. The standard Prius has a combined rating of 52 mpg.

• The top two of three trim levels in the Prime can be equipped with a Tesla-like vertically oriented 11.6-inch touchscreen that mimics the built-in tablet in Tesla’s Model S and Model X. It's one of the coolest features of any electric or hybrid car in existence — with the exception of the Tesla, of course.

• The Prime is more expensive than the standard Prius starting at $27,985 and topping out at $33,965 in the top Advanced trim. It can easily clear 35 grand with many of the bells and whistles that can be added as options. The standard Prius starts at $25,035 and tops out at $30,900.

Both vehicles have a combined gas engine/electric motor output of 121 horsepower outfitted with an Atkinson-cycle 1.8-liter inline 4-cylinder engine mated to a continuously variable automatic transmission. As you might assume because of its charging capabilities, the Prime gets a larger 8.8-kWh lithium-ion battery pack, compared to the 0.7-kWh pack in the Prius. Mileage is the key performance statistic of both the Prius and the Prius Prime with acceleration taking a back seat rated at 0-to-60 in 10 seconds with the Prius and 10.2 seconds in the Prime.

The Prius has obviously never been about its sportiness. But the Prius and the slightly larger and heavier Prime offer more rewarding driving traits than the outgoing generation. The new platform uses more high-strength steel contributing to a 60 percent improvement in torsional rigidity resulting in better handling as well as an improved coefficient of drag at 0.24. In addition, the Prius gets a new more sophisticated rear suspension replacing the third generation's beam-axle with a double-wishbone independent configuration.

Although the Prime is 6.5 inches longer than the Prius, the battery pack eats up interior space in the Prime. The Prius has more cargo space at 27.4 cubic feet compared to 20 cubic cargo feet in the Prime.

The interior retains the familiar Prius design with a center screen for navigation, audio, climate controls and readout at the top in the center of the dash displaying a large digital speedometer, gas gauge and charging information. Although we have always been put off a bit by the center-mounted speedometer, we love the new tablet touchscreen that is particularly fetching at night when it's vividly lighted with the navigation map and other controls. The Prime has a sophisticated living area with high-end materials including gloss black trim surrounding the large center screen.

The Prime can be purchased in three trim levels — Plus, Premium and Advanced. We would skip the Plus at 28 grand and opt for the Premium trim at $29,685 that brings numerous standard features including a power driver's seat, the large tablet touchscreen, premium synthetic leather seats, automatic headlights, keyless entry, satellite radio and wireless smartphone charging.

Our top line Advanced test model added such useful features as blind spot monitoring with cross traffic alert, head-up display, rain-sensing wipers and Premium JBL audio with 10 speakers and priced out for $34,584.

Essentials
Base price: $27,985, as driven, $34,584
Engine: 1.8-liter 4-cylinder, 2 electric motor/generators
Horsepower: 121 @ 5,200 rpm
Torque: 120 pound feet
Transmission: continuously variable
Drive: front wheel
Seating: 2/2
Wheelbase: 106.3 inches
Length: 182.9 inches
Curb weight: 3,375 pounds
Turning circle: 33.4 feet
Luggage capacity: 19.8 cubic feet
Fuel capacity: 11.3 gallons (regular)
EPA range: 55 city, 53 highway, 54 combined
0-60: 10.2 seconds (Car and Driver)
Also consider: Hyundai Ionic plug-in, Chevrolet Volt, Ford Fusion Energi

The Good
• Outstanding fuel economy
* 25 all-electric miles
• Excellent interior design

The Bad
• Bigger battery pack takes up interior space

The Ugly
• Very slow acceleration