LOS ANGELES — CarsDirect.com, an online automotive research and shopping service, is working in conjunction with Autos.com to provide consumes with a vehicle ranking system and more comparison tools. The new site has been designed especially for consumers still fine-tuning their list of potential vehicle purchases. “We have more than 100 professionals doing the research for car buyers — collecting the data, crunching the numbers and making it simple to understand,” said Bob Brisco, CEO of CarsDirect.com. The Website includes information on more than 500 models of cars, SUVs, trucks and vans. Twelve categories are used to rank vehicles, from invoice price and resale value to safety and performance features.