Customers browse in a used car lot in Glendale, California, Feb. 15, 2023.Mario Tama | Getty Images News | Getty ImagesDETROIT — Used car prices fell last month for the first time since October as gas prices rose amid the war in Iran.Cox Automotive’s Manheim Used Vehicle Value Index — which tracks prices of used vehicles sold at its U.S. wholesale auctions — decreased 1.6% last month compared with March and were up 1.8% compared with the same month a year earlier. Cox said affordability remains a key concern for buyers, which is driving increased demand for older vehicles and all-electric vehicles at Manheim auctions.Gas prices at the end of April were up $1.12 per gallon compared with a year earlier to a national average of $4.30 a gallon, according to AAA. They’ve continued to rise since, with the national average hitting $4.56 as of Thursday.”The conflict in the Middle East has now been ongoing for two months, and while energy prices backed off a bit in mid-April, they have reaccelerated to the upside: the price of gas just hit a high for the year and is up 47% since the end of February,” Cox Automotive chief economist Jeremy Robb said in a release. “Those higher prices are soaking up a lot of the extra money in consumers’ pockets, and currently there’s no end in sight.”Retail prices for consumers traditionally follow changes in wholesale prices, which Cox forecasts to rise at a historically stable rate of about 2% this year. The average listed price of a used vehicle was $25,390 as of March, according to Cox. That was up roughly $100 from February.The average listing price for a used EV remains more than $9,200 higher than the overall market, but new and used vehicle retailers have said the rapid rise in gas prices has led to higher EV sales following a slowdown after the end of federal incentives last year by the Trump administration.Manheim’s electric vehicle index was up 7.2% year over year and up 1.4% from March.April’s lower pricing follows a strong spring selling season, fueled by many consumers spending higher tax refunds to purchase or finance used vehicles, Cox said.Choose CNBC as your preferred sour …