A handful of alternative-fuel vehicles are among the fastest-selling late-model used cars this year, and the market for these vehicles may be approaching an affordability “sweet spot” in pre-owned.

That’s according to a study from iSeeCars.com, which analyzed more than 2.2 million sales of 1- to 3-year-old cars from January through May.

With average days on market at 19.7, the Toyota Prius plug-in hybrid was the fastest-selling late-model vehicle, one of five alternative-fuel vehicles to crack the top 10.

Its days-to-sell dropped from 38.1 in the year-ago period.

“The dramatic decrease in days on the market is at least partially due to the fact that 54 percent of these cars were sold in California and the distribution of the stickers that allow plug-in hybrids to be used in California's HOV carpool lanes with a single occupant has reached its limit, pushing up demand for used cars that already have this privilege,” iSeeCars chief executive officer Phong Ly said in the analysis.

Prices for the model also dropped 17 percent, which may have played a role as well.

Same goes for the Nissan LEAF electric, which was the second-fastest seller. Its days to sell dropped from 38.7 to 24.3, and its prices fell $2,219, according to iSeeCars.

Meanwhile, the Tesla Model S (26.1 days) was third, and the other two alt-fuel rides in the top 10 were the Lexus CT 200h hybrid in seventh (29.4 days) and the Toyota Highlander Hybrid in eighth (29.6 days).

Pricing ‘sweet spot’

In its analysis, iSeeCars breaks down the days on market by vehicle category, and compares each category to where it stood in 2015. The same chart also shows the year-over-year changes in price.

For electrics, the average days on market decreased from 37.6 to 29.2 and prices were down $3,830 (or 15.2 percent).

For plug-in hybrids, days-on-market fell from 42.5 to 40.7, with prices decreasing $1,214 (5.1 percent)

Hybrids took 38.2 days to sell, down from 43.2 days in the same period of 2015. Prices were down 3.7 percent (or $889).

Gas-powered vehicles took 42.5 days to sell, up from 41.3 days a year ago. Prices were off a percent (or $242).

“For these fastest-selling cars, the market may have hit a sweet spot where the pricing of these particular alternative fuel cars has dropped enough to make these cars more desirable,” Ly said.

Granted, Ly said that this doesn’t apply to all alt-fuel models.

But the iSeeCars analysis does point out gains in consumer confidence when it comes to performance, range, safety and battery life for alt-fuel vehicles.

And now, consumers may be feeling a bit more comfortable about their prices, too.