To come in as the world's least-expensive new car, India's widely publicized Tata Nano -- scheduled for Job 1 later this year -- also requires some significant engineering tradeoffs.

The powertrain of the 100,000 rupee (USD $2500) machine is built around a rear-mounted 623cc 2-cylinder 35 horsepower gasoline engine. Transmissions are a belt-driven continuously variable, or 4-speed manual.

Tata Nano

Putting that power to the ground inexpensively, however, apparently requires specifying wheel bearings limiting the recommended top speed to 70kph (44mph), with a warning that the service life of the bearings will be severely shortened by operating at higher speeds. Nano is said to be capable of 100kph (62mph).

Part of that limit can be put down to the Nano's use of 12-inch wheels. Such small diameter wheels and tires spin faster at a particular road speed than larger standard 14-inch or 15-inch wheels and tires -- which also means the wheel bearings are turning that much faster.

Another drawback to such small wheels is the requirement for similarly small brakes, putting a severe limit on safe stopping speeds.

Tata Nano wheel bearings are supplied by Tata Bearings, a separate operating division of Tata Group.