Safety
Everyone is concerned about the safety of their automobile. The government has established vehicle design requirements and guidelines such as periodic inspections and mandatory seatbelt use in many states. The government (as well as other consumer and insurance organizations) also conducts crash tests annually on various car models and provides data to the public. Vehicle crash test results and records of auto and tire recalls are available in a searchable database by year, make, and model:
Government Database
Insurance Institute Database

Fuel Economy
The government publishes an annual report on fuel usage of various makes and models:
Government Fuel Economy Report

Reliability and Maintainability
In order to service the market for spare parts, various organizations keep records of automotive reliability. An online database gives an overview of reliability by make, model, and year based on useage of spare parts. Since it takes several years and a significant number of cars to give good data, there may not be data for your car.
Vehicle Reliability Database
Most and Least Reliable Late Model Cars (Consumer Reports)

Depreciation
Depreciation is the amount by which your vehicle loses its value over time. If you buy a new car, keep it for five years in pristine condition, then trade it in -- the difference between what you paid new and the trade-in value is depreciation. Some cars retain their value better than others, because people will pay more for them in the used car market. To get an idea for the depreciation of a car you are interested in, use the site's New Car Central to find the new car MSRP, then find the Trade-in Value of the same model after 3 years and 5 years. If you keep your car for many years, depreciation may not be important. If you want to own late model cars, depreciation could be a major expense, especially if you trade your car after only 1 to 2 years.