Green cars can save their owners money by using less fuel, or--in the case of all-electric cars--none at all.
But as with any other car, the lack of fixed prices means there are better times to buy than others.
Certain models may be eligible for greater discounts at a specific time--potentially helping to save even more cash.
DON'T MISS: Green-Car Decline: Combined Hybrid, Electric Sales Started Falling Last June
As carmakers announce their May incentives, here are some noteworthy deals on hybrid, electric, and diesel models, via Cars Direct.
The 2015 Infiniti Q50 Hybrid remains among the best deals in its segment, with a $359 per month lease deal unchanged from April.
2015 Infiniti Q50
This lease includes a term of 39 months, with $3,599 due at signing and a cap of 10,000 miles per year.
That's made possible by around $3,000 in unadvertised lease discounts. The offer expires June 30.
Another luxury hybrid with a noteworthy lease deal is the 2015 Lexus CT 200h.
SEE ALSO: Toyota Prius Plug-In Production To End In June; New One Coming Next Year
Lexus shoppers can get a lease at $299 per month for 36 months, with $999 due at signing and a cap of 10,000 miles per year for the compact hatchback.
That amount comes after $2,500 in discounts, and is available until June 1.
Staying within the Toyota family, it's also now possible to lease a 2015 Toyota Avalon Hybrid for $329 for 36 months.
2015 Toyota Avalon Hybrid
That's with $1,999 due at signing and a cap of 12,000 miles per year.
This deal applies only to the Avalon Hybrid XLE Premium model, and represents a $20 cut in monthly lease payments on that model. The offer expires June 1.
In the electric-car segment, two of the best deals continue to be Chevrolet models.
MORE: Plug-In Electric Car Sales In Apr: Pace Continues Steady: FINAL UPDATE
As General Motors continues an unusually long run-out in anticipation of the all-new 2016 Chevy Volt, discounts on the current model remain high.
The lowest available lease payment is now $249 per month, down from $299 in April with the same 39-month term.
2015 Chevrolet Volt
The amount due at signing has dropped even more dramatically--from $1,449 to $500. A cap of 10,000 miles per year still applies, and the rate is good through June 1.
GM also cut the lease rate for the 2015 Chevy Spark EV compliance car, from $189 to $139 for 39 months.
Just as it was in April, that requires no money down but comes with a cap of 10,000 miles per year. The offer expires June 1.
Another compliance car sees a slight lease-price hike in May compared to April: The 2015 Fiat 500e goes from $139 to $169 per month for 36 months.
The $1,999 payment due at signing and annual 12,000-mile cap remain unchanged from April. The current offer expires June 1.
2014 Mercedes-Benz B-Class Electric Drive
The more widely-available 2015 Volkswagen e-Golf Limited Edition is available in more states than the Spark EV or 500e--and with the same lease deal offered last month.
That means you can still get one for $229 per month for 36 months, with $2,349 due at signing and a cap of 10,000 miles per year.
Note that the Limited Edition is the cheaper of the two e-Golf trim levels, below the SEL Premium. The offer for this model expires June 30.
While a 2015 model is on the way, the 2014 Mercedes-Benz B-Class Electric Drive remains on dealer lots in significant quantities.
To get rid of them, Mercedes is offering a lease at $306 for 36 months--with nothing due at signing and a cap of 10,000 miles per year--between now and June 1.
The 2015 B-Class Electric Drive will be virtually identical to the 2014, with some added features. However, it will be $124 more per month to lease.
2015 Volkswagen Jetta
2015 Volkswagen Jetta
On the diesel front, monthly payments for the 2015 Volkswagen Touareg TDI Lux have dropped slightly.
The SUV can now be leased for $549 per month--$10 less than VW's best April offer--for 36 months.
The $2,999 down payment and 10,000-mile-per-year cap are unchanged. This offer expires June 30.
Another Volkswagen that remains a good lease deal is the automatic-transmission 2015 Jetta TDI S.
It's once again available to lease at $219 per month for 36 months at 12,000 miles per year.
2015 BMW 328d sedan and Sports Wagon
It's also possible to lease the larger 2015 Volkswagen Passat TDI for $289 for 36 months, with $1,999 due at signing and a 12,000-mile annual cap.
That offer represents a $10 cut in monthly payments, and remains in effect until June 30.
Finally, the 2015 BMW 328d gets significant discounts in both sedan and Sport Wagon forms.
The sedan can be leased for $329 per month with $4,124 due at signing, while the wagon goes for $399 per month and $4,194 down.
Both lease terms are 36 months, with a cap of 10,000 miles. The lease offers expire June 30.
Right now, those looking to buy instead of lease can also get a $500 "Eco Credit" and $1,000 "Anniversary Credit," the latter in recognition of the 3 Series model line's 40th anniversary.