Honda AC-X plug-in hybrid concept has adaptive aerodynamics and autonomous driving mode


November 10, 2011

Few road-going cars have seen variable aerodynamics beyond the raising of rear  spoilers in a small number of very expensive exotic supercars - the AC-X looks set to change that

Few road-going cars have seen variable aerodynamics beyond the raising of rear spoilers in a small number of very expensive exotic supercars - the AC-X looks set to change that

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Any fan of Formula One racing will tell you that very small changes to the underside of an automobile can deliver major changes to the speed, handling and road-holding of said automobile. Due to the extreme costs associated with wind-tunnel development, varying the shape of racing cars is largely banned, and hence very few road-going cars have seen variable aerodynamics beyond the raising of rear spoilers for added down-force at speed, as used in the Bugatti Veyron and a small number of other very expensive exotic sports cars. One of Honda's latest batch of concept cars looks set to break with tradition though, by exploring this theme with front and rear bumpers which raise and lower to offer better aerodynamics depending on the speed.

Honda's line-up of concept automobiles, motorcycles, power and mobility products at the Tokyo Motor Show this year is very impressive, and the most interesting is the AC-X, a next-generation plug-in hybrid vehicle that at first glance appears to be relatively conservative for a vehicle designed to gauge public opinion on new technologies and designs.

Indeed, the entire release devoted to the AC-X in the lead up to its debut at the 43rd International Tokyo Motor Show next month reads as follows: "A next-generation plug-in hybrid vehicle which offers a more comfortable and enjoyable time in the vehicle during all driving situations, from urban to long-distance driving. With the choices of an "engine drive mode" for more aggressive driving or an "automatic drive mode" for more relaxed driving, the vehicle broadens the joy of mobility."

That's really not a lot to go on, but an examination of the photographs released by the Japanese manufacturer reveals some interesting technologies at work, and some of them might not be all that far from production models.

Among the captions showing the car from close-up front and rear angles was the "AC-X Adjustable Aerodynamics Bumper (front)" and "AC-X Adjustable Aerodynamics Bumper (rear)".

Closer examination of those images indicates the front apron and rear bumper/pan raise and lower to obtain aerodynamic advantage - no details have been provided, so Honda's press conference on the November 30 press day at Tokyo Big Sight should be well worth attending.

Honda must have upgraded its wind-tunnel facilities in recent times, because looking at the company's concept cars set for release at Tokyo, there's clearly a lot more emphasis on aerodynamic efficiency. Even the wheel covers on the AC-X appear to close at speed to ensure every last percentage point of aerodynamic loss is reduced, and the Micro Commuter Concept is also clearly brimming with minor aerodynamic detail intended to make the car as efficient as possible.

The same set of images released by Honda also indicates that the AC-X will also make use of what appears to be a very smart "key" which will be known as Honda Smart Connect. The functionality of the Honda Smart Connect has not yet been released, but clearly the dockable handheld device is carried by the owner of the vehicle and acts as a remote connection to the vehicle to indicate the state of charge of the next-generation plug-in hybrid, hence the "Smart Connect" name.

Further functionality will need to be pretty special, because the Smart Connect is the size of a smartphone, and if that's all that can be done with the key, Honda would be better off building a smartphone app and saving owners the effort of carrying yet another gadget. Logically, the Smart Connect will have far greater functionality - any ideas?

Several other innovations stand out from the images Honda has released, most notably that the steering wheel has been dispensed with and in its place is a pair of joysticks.

Most interestingly, two of the images indicate that the joysticks retract when the vehicle enters what Honda is calling "automatic driving mode", indicating that the AC-X features some form of autonomous or semi-autonomous mode which does not require the driver to steer the vehicle.

Finally, examination of the images indicates that in addition to a heads-up display projected onto the windscreen, there's also a panoramic 3D view of the surroundings generated not only onto the driver's display, but across the entire dashboard, even onto the passenger side of the vehicle, with the driver having a view of the immediate surroundings, but the passenger getting an aerial view of the city.

Needless to say, we're looking forward to seeing this one.

About the Author
Mike Hanlon Mike grew up thinking he would become a mathematician, accidentally started motorcycle racing, got a job writing road tests for a motorcycle magazine while at university, and became a writer. As a travelling photojournalist during his early career, his work was published in a dozen languages across 20+ countries. He went on to edit or manage over 50 print publications, with target audiences ranging from pensioners to plumbers, many different sports, many car and motorcycle magazines, with many more in the fields of communication - narrow subject magazines on topics such as advertising, marketing, visual communications, design, presentation and direct marketing. Then came the internet and Mike managed internet projects for Australia's largest multimedia company, (Australia's largest Telco), (Australia's largest employment site),,, and a dozen other internet start-ups before founding Gizmag in 2002. Now he writes and thinks. All articles by Mike Hanlon

That\'s all very impressive, Honda, but the idea of bumpers with moving parts is not exactly viable in the real world. Take a brand new car out of the dealer and the next thing that happens to it is that it gets bumped, even slightly, by other cars going in and out of parking spaces next to it.

So, chances are the owner will enjoy a working adjustable bumper for maybe a month or two... and then they\'ll just have to live with a \"dead\" bumper that is just too expensive to fix / replace.

Other than that, Honda as usual never ceases to impress us with what they come up with. As a happy owner of an 8th-generation Civic (european h/b model), I look forward to what will come out of their factories (and I personally look forward to a revised HRV :) )

Τριαντάφυλλος Καραγιάννης

I like the joy sticks. But sealed wheel covers? Why not go all the way and seal the wheel wells? Is the undercarriage sealed? What is the weight?


These are just aerodynamic crumbs that Honda believes may attract buyers just like Fords front shutters. The Cd is not given and neither is the Cd x A nor the weight of the vehicle. If the Cd is below 0.20, then then would have something aerodynamically sound but just looking at the car, I would find this hard to believe. The aerodynamics do not need to change but just be good. Fancy bumpers will not do the trick. What is needed is:

Lowering of the car weight An air divider in the front Undercarriage cover with slight front and back taper upwards Good, smooth front taper upward and rear top taper downward (more gradual than front taper) Side taper from front to back going inward

Basically the shape should look like a tuna which can swim up to 70 mph under water.

Adrian Akau

The joysticks look nice, but they take away the ability to turn hand-over-hand, which seems like a pretty big limitation for a car. As for the key, it shows a signal bar, so maybe it is a smartphone app... or a smartphone. I don\'t know how an app could be secure enough to use as a key though.

Charles Bosse

What\'s all this talk about monotonous driving? Of course it\'s monotonous...the speed limits are set too low, people don\'t drive carefully anyway, and there\'s too many cars on the road. I don\'t see why the...what?...oh. Oh, I see. Never mind.


No car shaped like a car is aerodynamic with one exception, the Aptera. And that looks to be dead in the water.


This is ridiculous without a boat tail and with those air-anchoring open wheel wells.

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