Used electric vehicles are seeing their prices erode, both on a retail and wholesale basis.

And not only did average retail prices of used EVs fall nearly 30% last month, but these vehicles have also become increasingly cheaper than used internal-combustion-engine vehicles.

According to iSeeCars.com, the price gap between used gas-powered vehicles and used EVs has increased the past four months.

February marked the first time that a 1- to 5-year-old used gas vehicle was more expensive than a used EV, iSeeCars data shows.

The difference at that point was 0.9%. In March, the gap grew to 3.5% and reached 7.4% in April.

Used ICE vehicles were 8.5%, or $2,657, more expensive than used EVs in May, according to iSeeCars.

What’s more, the price of a 1- to 5-year-old used EV fell 29.5% in May. Used ICE vehicle prices were down 6.1%, according to iSeeCars.

“There’s no denying the crash in used electric vehicle values over the past year,” iSeeCars executive analyst Karl Brauer said. “We’ve watched EVs prices fall between 30 and 40 percent since June of last year, while the average gas car’s price has dropped by just 3 to 7 percent in that same timeframe.”

Brauer added: “It’s clear used car shoppers will no longer pay a premium for electric vehicles and, in fact, consider electric powertrains a detractor, making them less desirable — and less valuable — than traditional models.”

The “crash” in EV prices is also happening in the wholesale market.

According to a midmonth reading of the Manheim Used Vehicle Value Index, wholesale prices of EVs through the middle of June are down 17% year-over-year. Non-EV prices are down 8.9%, with the overall market down 8.5%.

Parent company Cox Automotive said in a report accompanying the index that wholesale EV prices fell 7.1% in the first half of June compared to May, with non EVs up 0.4%.

In May, wholesale EV prices fell 16% year-over-year, according to the Manheim index, with non EVs off 11.6% and the overall market falling 12.1%