Photos: The wildest concept cars from Tokyo

Why take vitamins or do yoga when you can drive the RiN? Toyota designed this concept to promote the well-being of its occupants. The seats are built for perfect posture, and the steering wheel monitors the driver's mood, so the car can "bring you back to balance," according to Toyota.

We wouldn't think the locomotive looks of the Hi-CT qualify as "cool," but that was the intention of Toyota's designers. The concept is a plug-in hybrid, so we know that Toyota at least has an interest in this technology.

Built to hold recreational gear, the Hi-CT has an external rear deck to hold things like surfboards or BMX bikes. At the show, a couple of weird skate things were loaded on it. Hi-CT's plug-in hybrid power train gives it a high-voltage power source for amplifiers and blenders.

As its name suggests, the Mud Master-C was designed for off-road utility. Its tires give it a lot of clearance, and it has part-time four-wheel-drive, with a high and low settings. But its engine is a small 660cc three-cylinder, and its narrow stance won't be good for traversing slopes.

Daihatsu worked with Raita Suzuki, a professional cyclist, to build this mountain-bike-toting version of the Mud Master-C.

With four-wheel-drive and a center limited slip differential, the X-Head is designed for off-road use. But the real twist in this concept is its interchangeable load beds. Here, it's shown with a pickup bed, but Suzuki suggests you could also put on a camper bed, a crane bed, or any other application you can think of.

This concept's strange name is supposed to mean Round Box, an oxymoronic title that manages to be descriptive. Powered by a direct injection turbocharged engine, the R.D/B.X was designed to promote unity amongst its occupants.

The front seats are an interesting mix of bench and bucket, using the seat of the former and the backs of the latter. This configuration reinforces the unity concept, letting people in the front seats easily talk to and see the people in back. Plus, the roof comes off to give a sense of extra space, just in case there's too much unity in the cabin.

The NV200 is essentially a work van powered by a clean diesel engine. Its unique feature is a cartridge that slides out of the back, with legs to support it in the open position. With the cartridge open, the inside of the van becomes an office, with a desk that folds down from the wall and a couple of flat-panel monitors for a computer.

At the Tokyo auto show, the NV200 was equipped with a cartridge set up for scuba gear. Nissan suggests other diverse uses for it, such as a baker's truck, mobile T-shirt sales, or an Internet cafe on wheels.

With its glass canopy, the Puyo looks like it came straight out of The Jetsons. Honda is using it to explore the idea of a soft, gel-based body. While the rubbery exterior is intriguing, we doubt it would help much if you got hit by a Puyo doing 60 mph.