In some ways, September is all about transitions. Last week we officially moved from summer into fall, and a new school year is now under way. Car shoppers will also see some changes this month, as September car deals include outgoing 2012 models, as well as 2013 cars, trucks and SUVs that have made their way onto dealer lots.

Acura, Chevrolet, Hyundai and Mazda are all offering lease deals that will put you in a new car for under $300 per month. Leases on upscale small cars include the all-new 2013 Acura ILX, which is available for $239 per month for 36 months with $1,999 due at signing. Alternatively, you can lease the ILX for $300 per month with no money down. Affordable small car shoppers can also find zero-down lease offers in September. These include the 2013 Hyundai Elantra, which can be leased for $249 per month for 36 months with no money down.

Some new midsize cars and compact SUVs also have great September lease deals. The redesigned 2013 Chevrolet Malibu is available for $199 per month for 24 months with $2,219 down, and you can lease the all-new 2013 Mazda CX-5 for $239 per month for 36 months with $2,999 due at signing.

[Best Lease Deals]

Financing offers and cash-back rebates on outgoing 2012 models make up the bulk of September’s best car buying deals, with automakers like Ford, GMC, Toyota and Volkswagen offering no-interest financing and cash back. Shoppers looking for an affordable midsize car may like Ford’s September deal on the 2012 Ford Fusion, which is available with zero-percent financing for 60 months plus $1,750 cash back. Some retro-styled affordable small cars have good deals this month as well; the 2012 Volkswagen Beetle is available with zero-percent financing for six years.

Full-size truck and midsize SUV shoppers will also find good deals on 2012 models in September. You can get $2,000 cash back or zero-percent financing for 60 months on the 2012 GMC Sierra, and the 2012 Toyota Venza is available with no-interest financing for five years plus at least $1,500 cash back in most regions. If you need a three-row SUV, the 2012 Chevrolet Traverse is available with $2,000 cash back or zero-percent financing for six years.

[Best Purchase Deals]

While used car loans typically have higher interest rates, September used car deals include promotional financing on a number of certified pre-owned models. Subaru and Volkswagen both offer 1.99-percent financing on their certified used cars, while certified-used Toyotas are available with 2.9-percent financing for 60 months. If you’re shopping for a used luxury car, Mercedes-Benz also offers 1.99-percent financing on select certified pre-owned models.

[Best Used Car Deals]

If it’s been a while since you bought a new car, be sure to read up on how the market has changed. Then, check out our rankings to make sure that the car you’re getting is as good as the automaker’s incentive. With a little research, it’s easy to find a great car at an attractive price before month’s end.

Shopping for a new car? Check out the U.S. News rankings of this year's best cars. Then, look for a great deal on a new car by checking out this month’s best car deals. You can also find the best local prices in the area by using our Best Price Program. Also, be sure to follow us on Twitter, Facebook and Pinterest.