Why? Gas prices, of course. A recent study by AAA shows that the average price of gas is $2.82 a gallon nationwide.However, the price of oil continues to rise with a barrel of oil is selling now for close to $90 at the time of this post. This could mean that sales of mini-compact cars will rise, especially if prices return to above $3.00 a gallon. In fact, since May when the cost of gas was $3.23 a gallon, sales of mini-cars in the U.S. grew 20 percent with sales were led by Toyota's Yaris and Honda's Fit.