September means a change of seasons, as well as a change of model years.

As carmakers begin advertising their 2016 models in earnest, certain 2015 models that remain in inventory can get significant discounts.

That makes this a particularly good time to check on the best deals for green cars.

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Certain models continue to be heavily incentivized, while some get discounts that weren't available in previous months.

The deals listed below represent the best available for hybrids, plug-in hybrids, electric cars, and diesels for the month of September. Head over to CarsDirect for more information.

2015 Toyota Prius Liftback

2015 Toyota Prius Liftback

Hybrids

Toyota is offering significant discounts on two of its Prius "family" models this month.

The subcompact Prius C is available to lease for $159 per month for 36 months, with $1,999 due at signing and a 12,000-mile annual allowance.

In regions like Los Angeles, cash buyers can also get discounts of up to $2,000 on 2015 models as Toyota looks to clear remaining inventory.

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The 2016 Toyota Prius was unveiled in Las Vegas earlier this month, but buyers willing to stick with the outgoing model can get a significant discount.

Toyota is offering leases of the 2015 Prius Liftback at $199 per month for 36 months, with $1,999 due at signing and 12,000 miles per year.

Both Toyota lease deals run through October 5.

2015 Kia Optima Hybrid

2015 Kia Optima Hybrid

There are also up to $3,000 in cash discounts available in certain regions for the third-generation Prius Liftback.

The Kia Optima Hybrid is another model biding its time until a redesign version appears, but for anyone not willing to wait, now appears to be a pretty good time to scoop one up.

Between now and November 2, a 2015 Optima Hybrid can now be leased for $209 a month for 36 months.

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That's with $1,999 due at signing, and 12,000 miles per year.

Cash buyers can get up to $3,000 in discounts, which is about double what is available for a comparable Toyota Camry Hybrid, according to CarsDirect.

There's also a $500 "conquest bonus" for buyers switching from certain non-Kia models.

2015 Ford C-Max Energi

2015 Ford C-Max Energi

Plug-In Hybrids

The 2015 Ford C-Max Energi is still the best deal among plug-in hybrids, thanks to a slight price cut by Ford.

Until the end of September, the C-Max Energi can be leased for $139 a month for 36 months, with $3,049 due at signing and a 10,500-mile annual cap.

That's a $20 cut in monthly payment and a $50 cut in money down compared to last month.

That means the C-Max Energi now has an effective monthly cost that's $87 less than the Ford Fusion Energi mid-size sedan (which uses the same powertrain), according to CarsDirect.

It's also $101 less than the Toyota Prius Plug-In Hybrid, which is out of production awaiting the arrival of a new model based on the fourth-generation platform.

2015 Volkswagen e-Golf Limited Edition

2015 Volkswagen e-Golf Limited Edition

Electric Cars

The 2016 Volkswagen e-Golf represents one of the best electric-car deals this month, with a lease at $229 per month for 36 months.

That deal includes $2,349 down, and an allotted 10,000 miles per year, and applies through November 2.

Volkswagen dealers also have $5,000 in unadvertised discounts that they can apply at their discretion, so in this case it pays to shop around.

The e-Golf is still only available at certain dealers in California, Connecticut, the District of Columbia, Massachusetts, Maryland, Maine, New Jersey, New York, Oregon, Rhode Island, and Vermont.

Another potential good deal is the Fiat 500e, which is available to lease at $169 a month for 36 months, through September 30.

That's with $1,999 due at signing, and an annual limit of 12,000 miles.

The 500e remains available only in California and Oregon, though.

2015 BMW 328d sedan and Sports Wagon

2015 BMW 328d sedan and Sports Wagon

Diesel

The best diesel deal this month is the 2015 BMW 328d, particularly in all-wheel drive xDrive Sports Wagon form.

This model can be leased for $379 per month for 36 months, with $4,304 down and 10,000 miles per year.

BMW is also adding $500 in "Build Out Cash" this month, bringing incentives for cash buyers to $2,000.

All of these incentives and deals remain in effect until September 30.

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