For our popular car picks, we started with our own favorites based on test-drives. We also used Kiplinger’s proprietary ranking system to assess cars for value, performance and safety. From vehicles that made the used-car cut, associate editor Jessica Anderson, author of our Drive Time column, narrowed her selection to those that had the friendliest combination of pricing, fuel economy and reliability. To choose the best green cars, we didn’t stick slavishly to hybrids but also included diesels, which get up to 40% better fuel economy than gasoline-engine vehicles. Those selections were “more scientific,” says Jessica, because she pulled all the 2010 models into statistical rankings and “let the chips fall where they may.” Cars that were close in points got extra credit if we liked them in our test-drives. -- Janet Bodnar, Editor, Kiplinger's Personal Finance

Whether you are looking to save money by buying a used car or just save on gas, these are our best cars for the price.

Best Used Cars

If you want: Great gas mileage in a small package

Car: 2006 Pontiac Vibe ($9,614)
Why we like it: GM’s twin of the Toyota Matrix costs less but has the same fuel-efficient engine and generous cargo space.

If you want: A budget-friendly family car

Car: 2007 Hyundai Sonata GLS ($10,565
Why we like it: This car competes with the Honda Accord and Toyota Camry, but it comes with a lower price.

If you want: Luxury at an affordable price

Car: 2006 Acura TL ($21,091)
Why we like it: The reliable TL offers stellar resale values, standard safety features and fuel-efficient performance.

If you want: A crossover SUV

Car: 2005 Toyota RAV4 ($13,144)
Why we like it: Toyota’s small crossover consistently tops its class for its mix of functionality, fuel-friendliness and value.

Best Green Cars

Ford Fusion Hybrid: ($28,350, 41 mpg city/36 hwy) Besting the Camry hybrid by 8 mpg in the city, Ford’s family sedan has optional leather seats and a cool dashboard display that sprouts leaves as your mileage improves.

Audi A3 2.0 TDI: ($30,775, 30 mpg city/42 hwy) Audi adds a diesel engine to its entry-luxe wagon for 2010. The A3 cleans up its act with 30% better fuel economy than its gas-engine sibling and boasts a hefty 236 pound-feet of torque.

Lexus RX 450h: ($42,535, 32 mpg city/28 hwy) With 30 mpg in combined city and highway driving, the redesigned 450h boasts 20% better fuel economy than the old RX hybrid. Lexus’s good looks and ten airbags are standard fare.

Mercedes GL350 BlueTec: ($60,825, 17 mpg city/23 hwy) Refreshed for 2010, the GL has a six-cylinder diesel that boasts the torque of an eight-cylinder engine. It can haul seven people, and the third row flips down for 44 cubic feet of cargo space.