Detroit LIVE: 45 mpg 2013 Volkswagen Jetta Hybrid

Volkswagen's new Jetta Hybrid is its most efficient model. Details inside.

About 18 months after debuting its redesigned Jetta sedan, Volkswagen has finally taken the wraps off of its most fuel-efficient model: The 45 mpg Jetta Hybrid.

Starting with an ultra compact 1.4-liter turbocharged gas engine, the hybrid system adds a 27 horsepower electric motor and a 1.1 kWh, 220-volt lithium-ion battery behind the rear seat. The gas engine is rated at 150 horsepower and 184 lb-ft. of torque on its own, and VW says it's a particularly torquey unit since the maximum grunt is available from 1,400 to 3,500 rpm.

In ideal, full battery conditions, the Jetta can motor up to 44 mph for 1.2 miles on purely electric power before the gas engine kicks on. An E-mode button on the center console locks the Jetta in EV mode when conditions allow. The battery that supplies power to the electric motor is tucked behind the rear seat. It weighs 80 lbs. and features its own cooling fan and VW is quick to note that it is disconnected when it's not in use or of the vehicle is wrecked.

VW's seven-speed dual-clutch automatic transmission - called DSG - sends power to the front wheels. To recharge the battery, the Jetta features regenerative brakes at all four wheels, as well as start/stop technology that shuts the engine off when the vehicle is brought to a stop in traffic. Heating, air conditioning and audio are not affected by the shut down engine. The gas engine also shuts down when the driver is coasting at speeds under 84 mph to save fuel by eliminating driveline drag.

For drivers looking for a little more sport in their hybrid, VW says that the shifter can be moved to a Sport mode that boosts available power at the expense of fuel economy. Combined, the two engines provide up to 170 horsepower when Sport is selected.

The hybrid powertrain is the fifth motivation system available in the Jetta, complementing gas 2.0-liter four-cylinder, 2.5-liter five-cylinder and 2.0-liter turbo four-cylinders, as well as a diesel 2.0-liter turbo four-cylinder.

Overall, VW says that the Jetta Hybrid tips the scales at 3,310 lbs., or about 221 lbs. more than a non-hybrid model.

As a result of its relatively low weight and reasonably powerful engine, VW says that the Jetta Hybrid can accelerate from 0-60 mph in 9 seconds flat.

Charting the changes
Retaining the appearance of the standard North American-market Jetta sedan, the Hybrid's exterior modifications are limited. A new front air dam, rear diffuser and rear spoiler help it cheat the wind to a Cd about 10 percent lower than normal. In addition, special 15-inch alloy wheels ride on low rolling resistance tires and a new grille features a blue-backed VW badge.

Inside, Jetta Hybrid features a unique instrument cluster with a special menu that displays energy flow and battery charge state data.

A power meter replaces the tachometer to show drive modes like Ready, Charge, Eco, Boost and Off. In addition, VW has utilized the Jetta Hybrid's audio system to display a "zero emissions" menu that shows how long the car has been driven with the gas engine shut off entirely.

Look for the 2013 Volkswagen Jetta Hybrid to go on sale at the end of 2012 in North America. As the only true hybrid in the compact sedan class, its rivals range the gamut from purpose-built hybrids like the Toyota Prius and Honda Insight to high-mpg gas and diesel compacts like the Chevrolet Cruze Eco, Mazda Mazda3 Skyactiv and even its Jetta TDI sibling.

Live images by Chris Doane.

Official Images