DALLASThe purchase and financing of an average priced new vehicle took 23.8 weeks of median family income in the third quarter 2010, according to Comerica Bank’s Auto Affordability Index.

The average total cost of buying and financing a new car decreased by $300 to $27,600, a 1.4 percent decrease from the second quarter. Median family income is estimated to have increased 0.2 percent in the third quarter. The second quarter reading was revised up 0.5 weeks to 24.1 weeks of median family income.

“With the recovery slowing and confidence shaky, consumers bought somewhat less expensive cars on average in the third quarter, thereby contributing to the improvement in affordability,” said Dana Johnson, chief economist at Comerica Bank. “However, the cost of financing new cars rose somewhat, as buyers extended the length of their car loans by a month and increased the average size of their loans by $200.”

Comerica Bank’s report incorporates the latest data on consumer spending on light vehicles and on the terms available on auto loans.