Cars prices have accelerated steadily for the last decade, thanks to an increasing reliance on technology and ever-more luxurious interiors. Even a compact car can easily cost more than $20,000. Shifting into reverse, French auto maker Renault decided in 1998 to design a modern car with state-of-the-art safety features costing only 5,000 euros [$6,000]. Renault's strategy was to create a car for people in emerging markets who have never owned an automobile -- some 80% of the world's population. But when the $6,000 Logan was unveiled last fall, it wowed West Europeans, too. This June, the much-in-demand Logan, which sells...