I'm an online Consumer Reports subscriber. Here's their list of best used cars:
Acura Integra
Acura MDX
Acura RL
Acura RSX
(except ‘06)
Acura TL
Acura TSX
Buick Regal
Chevrolet Prizm
Honda Accord
Honda Civic
Honda Civic Hybrid
Honda CR-V
Honda Element
Honda Odyssey
Honda Pilot
Honda Prelude
Honda S2000
Infiniti FX
Infiniti G20
Infiniti G35
Infiniti I30, I35
Infiniti QX4
Lexus ES
Lexus GS
Lexus GX
Lexus IS
Lexus LS
Lexus RX
Lexus SC
Lincoln Town Car
Mazda Millenia
Mazda MX-5 Miata
Mazda Protegé
Mazda3
Nissan Altima
Nissan Maxima
Nissan Pathfinder
Pontiac Vibe
Scion xB
Subaru Forester
Subaru Impreza
Subaru Impreza WRX
Subaru Legacy
Subaru Outback
Toyota 4Runner
Toyota Avalon
Toyota Camry
Toyota Camry Solara
Toyota Celica
Toyota Corolla
Toyota Echo
Toyota Highlander
Toyota Land Cruiser
Toyota Matrix
Toyota Prius
Toyota RAV4
Toyota Sequoia
Toyota Sienna
Toyota Tundra

And Worst Used Cars:
BMW 7 Series
BMW X5 (V8)
Chevrolet Astro
Chevrolet Blazer
Chevrolet Express
Chevrolet S-10 (4WD)
Chevrolet Venture
Chevrolet Uplander
Chrysler
Town & Country (AWD)
Dodge
Grand Caravan (AWD)
GMC Jimmy
GMC Sonoma (4WD)
GMC Safari
GMC Savana
Infiniti QX56
Jaguar S-Type
Jaguar X-Type
Jeep Grand Cherokee
Kia Sedona
(except ‘06)
Land Rover Discovery
Land Rover LR3
Lincoln Aviator
Lincoln Navigator
Mercedes-Benz CLK
Mercedes-Benz
M-Class (V8)
Mercedes-Benz
S-Class (V8)
Mercedes-Benz SL
Nissan Armada
Nissan Titan
Oldsmobile Bravada
Oldsmobile Cutlass
Oldsmobile Silhouette
Pontiac Aztek
Pontiac Trans Sport
Pontiac Montana
Pontiac Montana SV6
Volkswagen Cabrio
Volkswagen Jetta
(turbo, gas)
Volkswagen Jetta (V6)
Volkswagen
New Beetle (4-cyl.)
Volkswagen Touareg
Volvo XC90 (6-cyl.)