Translation:My car is not as new as my friends' one.
Fair and smart question: when you buy a car it is "toute neuve" (brand new = un-used).
After a while, it becomes "pratiquement neuve", "encore neuve", "presque neuve" (no scratch, still shining, looking brand new... whichever the numbers on the meter).
So comparisons are made possible: "presque aussi neuve", "pas aussi neuve"... what counts is the date of purchase + the overall look at the time of comparison.
That's how men deal with their (second) object of pride...
Does that help?
In French, a plural subject can have a singular object and it means "one each" or "2 or more share the object". It would not be irrelevant that 2 friends can share a car though.
Note that in English, with "my friends' cars" you don't know either whether each of your friends has one car or several.