We often say that the biggest gains in fuel efficiency are to be made by the least efficient vehicles--and recently, several automakers seem to be taking that message to heart.

Over the last few days, there seems to have been a constant stream of trucks, luxury sedans and SUVs all offering improved economy and lower emissions through various means. The latest to join this collection is the BMW Concept5 X5 eDrive, appearing at the Frankfurt Auto Show next month.

Based on the BMW X5 SAV, the Concept5 eDrive uses a plug-in hybrid drivetrain.

At its heart is a four-cylinder TwinPower turbocharged gasoline engine, a 70 kW (95 hp) electric motor, and a lithium-ion battery pack. The latter is said to power the car for up to 19 miles on electric power alone--under European testing conditions--at speeds of up to 75 mph.

No combined top speed is quoted, but BMW says the car will complete the 0-62 mph sprint in "under 7 seconds"--on a par with the diesel BMW X5 xDrive35d. Significantly better is the Concept5 eDrive's combined fuel economy at just under 62 mpg. As usual, this figure is based on European testing and includes the car's electric range--so real-world, hybrid-only economy would vary wildly from this figure.

It's the second vehicle to feature BMW's eDrive technology, following last year's Concept Active Tourer. The X5 adds xDrive all-wheel drive to the mix, not only maintaining the X5's pseudo off-road image but aiding its handling, with fully variable distribution of drive between front and rear wheels.

ECO PRO mode returns, helping the driver to use as little energy as possible, and it's paired with a hybrid-specific Proactive Driving Assistant, warning the driver of upcoming route data, speed restrictions and traffic. BMW has also included a hold mode letting drivers maintain electric charge for possible inner-city restrictions.

There's an unwritten rule with BMW's Concept-badged cars: If the 'concept' looks essentially like a production car, then it probably is a production car.

This may also explain the spy shots one of our readers took earlier this month, featuring a BMW X5 covered in camouflage and wearing 'Hybrid Test Vehicle' stickers. We expected the model was just the latest in BMW's ActiveHybrid range...but will the next hybrid X5 be a plug-in model?

The BMW Concept5 X5 eDrive joins BMW's i3 electric car and i8 plug-in sports car at the Frankfurt Auto Show next month.


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