The end of the year holidays aren't just a great time to get a new vehicle, there are good deals available on used cars then too.

Is there anything more elusive than a “good deal” when it comes to buying a car, especially a used car? There are many variables that go into getting an automotive “unicorn,” and when you buy a vehicle is one of those key factors.

In analyzing more than 40 million used-car sales from 2013 to 2015, iSeeCars.com, a deal-ranking site for used vehicles, compared specific times of the year, such as days of the month and week, to determine whether customers can score more or fewer deals than average. (A deal was defined as a savings of 5% or more.) Based on those findings, the site listed the 10 best times to land a deal.

They also figured out the worst time to buy a used car. If you’re in the market now, you might want to wait until the weather cools off, according to what they found, before you start prowling a dealer’s used car selection.

“It’s always nice to save money, and when you are buying something as expensive as a car, saving even 5% of your purchase, or $952 off the average price of $19,040, can really add up,” said Phong Ly, CEO of iSeeCars.com.

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Cold weather must mean cold sales because the top times were all in cold, or at least cooler, weather months with Black Friday leading the way. Yup, get a 50-inch flat screen for $200 and put that into the used car you just bought. There are 33.1% more deals than average on Black Friday, the survey noted.

When you see fireworks, it is unlikely they're being used to celebrate the awesome deals on used cars.

Other top times include:

• Veteran’s Day (32.5%)
• Thanksgiving (30.6%)
• Columbus Day (30.5%)
• Martin Luther King Jr. Day (29.4%)
• Christmas Eve (28.7%)
• November (26.9%)
• December (23.5%)
• Christmas (21.4%)
• New Year’s Eve (21.3%)

Ly noted that many of the holidays are prime times because dealers are looking to move inventory and the holidays are often observed on a Monday, giving potential buyers an additional day to shop for that new ride.

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Conversely, when the weather warms up, so does the demand for new vehicles. It also means the incentives to lower prices or cut a buyer a good deal goes down. The site note the worst times to get a good deal included:

• Fourth of July (28% fewer deals than average)
• Mother’s Day (27.5%)
• April (27%)
• May (26%)
• June (23.6%)
• Easter (22.2%)
• Good Friday (21.6%)
• Memorial Day (18.3%)
• Father’s Day (18.3%)
• July (11.5%)

The end of summer, leading into the cooler months, is often when the bulk of new model year vehicles begin arriving at dealerships in large volume. With those new cars, trucks and sport-utilities calling buyers names, the trade-ins start hitting dealer used car lots.

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“After the current new car model year comes to a close around August, consumers start trading in their used cars in higher quantities, thereby increasing the number of used cars available after the summer and driving dealers to make better deals.”