U.S. median-income car buyers can reasonably afford only about half the current $30,339 average transaction price for a new vehicle, according to Requisite Press, a financial-data tracker.

But for consumers looking for the deal of the month, it’s the Ford Fiesta Hatchback S, according to TrueCar’s analysis of transaction prices. The Fiesta’s market average is running $2,526 below its $15,425 sticker.

That puts it on the sunny side of Requisite’s latest Auto Buyer’s Affordability Index of 52.1, meaning the maximum affordable price for a prudent consumer is $15,795, based on a median income of $53,043.

The index is predicated on a prudent buyer following the so-called 20-4-10 auto-financing rule. That calls for a minimum 20% down payment, maximum 4-year loan term and monthly payments of no more than 10% of gross household income.

Personal finance experts recommend following the rule to maintain financial security and avoid high interest costs, Requisite says.

Affordability information is increasingly important to consumers in light of higher loan amounts and longer payback periods, the company says.

Some lenders worry about extending loans to the likes of 84 months because it increases the chances of some borrowers defaulting. Dealers dislike stretched-term loans, saying they take consumers out of the market too long.

Credit scorer FICO notes a growing pessimism among lending risk managers regarding auto-loan delinquencies, Requisite says.

The ’14 Fiesta hatchback model is small and entry level, but its transaction price and estimated $185 monthly payment will keep most car buyers out of deep debt.

TrueCar rates it May’s No.1 deal because its $12,899 market average transaction is 16.4% below MSRP.

“Small and midsize SUVs have been extremely hot this spring,” says Larry Dominique, TrueCar’s executive vice president who also is residual setter ALG’s president.

“But with gas prices increasing in the short term and automakers starting to discount vehicles that will be redesigned, expect to see sizable savings on car segments,” he says.

Following the Fiesta, TrueCar’s other cited top deals on ’14 models based on below-MSRP transactions are:

  • Toyota Camry sedan. Its average market price is $20,733. That’s 10.8% off MSRP.
  • Kia Sorento SUV. Its averaging $22,383, or 10.5% under sticker.
  • Acura ILX luxury car. The average selling price of $29,237 is 10% below MSRP. 

The market average is based on the national average of recent vehicle transactions, including destination and delivery charges after incentives that are subject to change. Not included are taxes nor title, licensing, documentation and processing fees.

sfinlay@wardsauto.com