One of the truisms of consumer technology is that it usually starts out in the industrial or military sectors, and stays there until it’s small and cheap enough for normal people to buy. Or, at least, until the market demands that it be made small or cheap enough to buy. That’s been true of internal combustion engines, computers, GPS and whole drive systems — drive systems like those used in one of the oldest forms of motorized transportation on Earth.

Diesel-electric hybrid systems have been known performers in locomotives for almost a century now. Apart from the fact that diesels are more efficient than gas engines to begin with, they make much better generator engines. Gas engines are usually most efficient at or near wide-open throttle. Diesels are just the opposite, consuming fuel most efficiently while idling. Locomotive engineers figured out a long time ago that coupling a diesel generator to an electric powertrain was the cheapest way to burn hydrocarbons; and yours truly has been waiting on this for years. Finally, predictably, it was Audi (my favorite major car company) that brought to market a "solution" painfully obvious even in Ferdinand Porsche’s time. Or, if not then, at least when Audi itself used a diesel-* electric car to win LeMans several times.

Yes, the "e-tron" Q7 is upon us — finally .

Continue reading to learn more about Audi’s future electric car.

The System

Audi debuted the e-tron Q7 crossover at this year’s Geneva Auto Show, and you have to imagine the reaction was "Well, it’s about damned {}time ." Audi has long since run away with the title of Best Diesel Manufacturer in the World, and its 3.0-liter TDI V-6 has certainly contributed to the reputation. As fitted in the Q7, the turbocharged and direct-injected diesel makes 258 horsepower and 443 foot-pounds of torque. For perspective, those numbers are slightly better than Ford’s original 7.3-liter Powerstroke diesel V-8.

Audi’s excellent engine couples to a fairly unique parallel hybrid system. Actually, it’s sort of parallel. It’s also a series hybrid, and a mild hybrid.

The first of the two electric motors is a disc-shaped unit sitting between the eight-speed Tiptronic transmission and the engine. The Tiptronic already has an interesting "freewheeling" function that allows the vehicle to coast without resistance when called for. What makes it interesting is that the freewheeling function ties into the adaptive cruise control, which itself ties into the GPS nav system. This allows the Q7’s system to react to the roads it’s on and the traffic around it by changing the way it coasts or brakes. Audi says this integrated system, in itself, is worth a 10 percent improvement in fuel economy.

(Saab geeks will note that this isn’t the first time a manufacturer has incorporated a freewheeling mechanism in the drivetrain. Fortunately, though, Audi isn’t planning on forcing drivers to choose between fried brakes and a fried engine.)

The first electric motor can drive the transmission and wheels via a clutch, it can be driven by the TDI engine and act as a generator, or it can help the engine out as an intermediary by supplying extra power. The freewheeling mechanism allows the electric motor to do all of the "engine" braking, regenerating and returning power to the lithium-ion battery pack in the process.

The second electric motor is adjacent to the rear axle. With an electric motor both before and after the transmission, this is an incredibly versatile system. All things considered, it’s best to avoid sending power through a transmission; even one designed as efficiently as the Tiptronic sucks up power that should go to either acceleration or brake regen. The rear-axle motor also bypasses the standard Quattro AWD system, further reducing losses. Direct-driving the rear wheels in this way should make for a significant 20 percent improvement in energy efficiency while running at low speed in electric-only mode.

Speaking of which, the Q7’s lithium battery pack should be good for a full 35 miles of electric-only range. That’s an important figure; the Q7 is a plug-in hybrid, and most peoples’ two-way daily commutes are between 25 and 35 miles. The U.S. is on the higher end of that; Europeans average 15 to 25 miles both ways. So, with 35 miles of electric-only range and a plug, it’s quite conceivable that the average customer will end up driving on electric power all or most of the time. Shame — seems like a waste of a perfectly good TDI. If you can keep your foot out of it.

Not that you will — with a combined 375 horsepower catapulting you to 60 in just under 6 seconds and to a top speed of 140 mph, odds are good you’ll end up spending as much time challenging WRX’s as your own fuel economy records. However, once you get tired of that, you should see a stunning 166 mpg and 50 g/km of carbon emissions.

Granted, that "166 mpg" is an energy equivalence assuming that the Q7 spends some time plugged in, and that you’re not constantly flooring the thing. But assuming you’re a normal person, driving in a normal way on a normal commute, the Q7 represents a stunning mixture of technology, economy and eye-watering performance.

Why it matters

Cynics will point out that no hybrid ever delivers the promised fuel economy; they’ll say the Q7 is just a gimmick to register a lower carbon tax rating, and get around congestion charges like those in London. Fair enough. That’s true. It probably would be possible to get 50 mpg or less in the Q7 if you misuse the thing.

However, this crossover is a fine tool for fuel economy, fun and practicality in equal measure. It won’t be cheap — estimates right now run close to a hundred grand American. It will probably take a long time for the e-tron to offset its $35,000 premium over the current top-of-the-line Q7 crossover. Probably a bit less time if you live in Europe, where taxes, insurance and congestion charges could add thousands of euros a year to the running costs versus a standard Q7. Even so, realistically, don’t expect the e-tron hybrid system to begin to pay itself off until your youngest child graduates high school.

But hey, new technology is expensive...even when it’s not precisely "new." And look at it this way: you could spend a decade sending $50K to the government and Saudi Arabia, or you could donate that same $50K to develop more hundred-year-old train technology for use in automobiles.

Who knows? At this rate, in another 50 years, we might see the Audi Q7 Monorail.

Buy stock in magnets now.

Audi Q7 e-tron 3.0 TDI quattro

2016 Audi Q7 e-tron 3.0 TDI quattro High Resolution Exterior Wallpaper quality
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Source: AutoExpress

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