Finally, small is gaining some critical mass.

After decades of lackluster sales in the bigger-is-better U.S. auto market, tiny cars are surging in popularity -- even as the overall auto industry declines. Sales in the compact-car segment, which includes the Toyota Motor Corp. Yaris, Honda Motor Co. Fit and General Motors Corp. Chevrolet Aveo, rose 33% in the U.S. last year.

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