Of the four prestige German auto brands, BMW is clearly the most aggressive in its plans for plug-in electric cars in various segments.

Last year it launched the BMW i3 battery-electric small hatchback and the sexy BMW i8 plug-in hybrid sport coupe.

According to reports out of Germany, the next vehicle in the "i" family will be called the BMW i5--and it will be a plug-in hybrid sport sedan that can run the majority of the time on electric power only.

DON'T MISS: 2016 BMW X5 xDrive 40e Plug-In Hybrid SUV To Debut In Shanghai This Month

But the putative i5 sedan will have far more electric capability than the 2016 BMW X5 xDrive 40e plug-in hybrid SUV to be launched this month.

That's BMW's first of several plug-in hybrids with an estimated 12 to 15 miles of electric range under low to moderate acceleration and around-town speeds.

In an article in the German magazine Autobild, as translated by BMWblog, the i5 is described as a unique body and powertrain using some of the underpinnings of the next BMW 5-Series sport sedan.

The crucial feature, however, is that it will use the Power eDrive second-generation plug-in hybrid system the company demonstrated at its Technology Days last fall.

2016 BMW X5 xDrive 40e

2016 BMW X5 xDrive 40e

That system, which has received relatively little notice in the U.S. thus far, flips the idea of a plug-in hybrid on its head.

Today's plug-in hybrids use a gasoline engine that gets assist from electric motors, which also provide 12 to 25 miles of all-electric range under low to average power demand.

But the Power eDrive system is designed to offer far more electric-only driving for up to 50 miles, with the gas engine used only under maximum acceleration and at highway speeds.

The BMW i5 is said to switch on its engine under maximum power demand only above 36 mph (60 km/h); below that figure, it's electric-only.

ALSO SEE: BMW Unveiled Not Just One, But Three Plug-In Hybrids Last Week (Dec 2014)

In the demonstration last November, BMW executives called Power eDrive the next stage of vehicle electrification.

Its sole goal is to maximize the time a vehicle spends in electric-only mode--which naturally boosts its efficiency.

The system shown employed  a 200-kilowatt (268-horsepower) electric motor to power the rear wheels of a BMW 5-Series GT development prototype.

That amount of power plus a battery pack of up to 20 kilowatt-hours would enable the vehicle to run much of the time solely on electric power.

BMW 5-Series Gran Turismo Power eDrive prototype

BMW 5-Series Gran Turismo Power eDrive prototype

For longer distances, a combined engine-motor-transmission combination powers the front wheels as well, meaning Power eDrive vehicles are technically through-the-road hybrids as well.

The front motor alone is rated at 150 kW (201 hp), on top of the engine output. With a total output of more than 500 kW (670 hp), BMW says the vehicle can operate solely on electric power throughout fully two-thirds of its usage cycle.

In other words, regulatory requirements for vastly reduced carbon emissions have led to a solution that maximizes the electric capability of plug-in hybrids, giving owners more of what they want: electric-only drive without the engine switching on.

MORE: Tesla And BMW: Natural Competitors In Electric Cars, One Day

According to Autobild, the vehicle in which this powertrain will be installed is said to have the sleek proportions of a 6-Series Gran Coupe.

But it will use some of the underlying structure of the long-wheelbase 5-Series sedan favored in China.

It's not entirely clear that the vehicle described--which is clearly under development, the magazine says--will be called a "BMW i5," since it may not use the carbon-fiber-reinforced plastic (CFRP) body shell and aluminum rolling chassis of the i3 and i8.

2015 BMW i8, test drive in greater Los Angeles area, Apr 2014

2015 BMW i8, test drive in greater Los Angeles area, Apr 2014

But as a vehicle that can operate wholly in electric mode under 35 mph, it's clearly a step toward greater electrification.

The i5 (or whatever it is finally dubbed) is expected to arrive during 2018, Autobild wrote, and BMW is said to be targeting 30,000 units a year at a price in the low six figures.


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