The Sonic, which debuted last summer boasting a starting price under $14,000 and fuel efficiency of up to 40 mpg, has been a smash hit thus far in 2012. In March, GM sold more than 100,000 cars that get 30 mpg or better, with rising sales of the Sonic helping the cause. After selling a then-record 7,900 Sonics in February, 8,251 Sonics were sold in March, as the model grabbed 14% of the subcompact segment.