A few items you'll also need to consider are the automatic transmission (if you get one) or the clutch (if you get a stick shift). If you consider buying a car with an automatic, first check the color of the fluid on the transmission dipstick. If the fluid is brown or smells burned at 40-50K miles; I would not buy that particular car; as the transmission probably will fail before long. If it is a stick shift; the clutch should begin to engage while the pedal is still close to the floor. If the pedal has to come a long way up before the car begins to move; the clutch will probably need replacement soon.
I would also remove the radiator cap, and check the color and level of the coolant. The coolant should have been changed by this time; so it should be clean, and the radiator completely filled. If the coolant is dirty, or looks like plain water, or the level is low; you can expect premature probems with the radiator and cooling system.
Also remove the oil filler cap, and look at the underside of that cap; if it is coated with gray sludge, then there either may be a head gasket leak, or the car has had mostly short trip use which did not warm the engine up enough to boil the moisture out of the oil. Either of those situations will lead to shortened engine life.
The brake fluid should also have been changed by this time. If it has; the fluid in the master cylinder will look clean. If it has never been changed in 6-7 years; the brake fluid will look dirty. And that could create premature problems with the brake hydraulic system.
The 40-50K miles in 6-7 years that you listed is about half the national average (of 12,000 miles per year). Such low mileage is more likely to be found in a car that just was driven around town; which is the worst kind of driving for an engine. I would much prefer to buy a car that age, which had been driven on longer trips, was properly maintained, and had 70,000 miles on it. I would expect the mechanicals to last a longer number of total miles on such a car. And if you find a car that is being sold by the original owner, and you ask and find that they used the same brand of oil at every oil change since the car was new; I would strongly favor that car. Mixing brands of oil is a sure way to shorten engine life. And that is why I would go to great lengths to find such a car; and I would continue using the same brand and weight of oil, for as long as I owned the car. (I say this, after buying my current car at 58,000 miles, when it was 2 years old. I've continued using the same oil as the original owner; and the car now still runs great, and the engine has never needed mechanical work; at 275,000 miles!!!)