Tried out (6 letter answer)
The answer TESTED is uncommon, appearing about once every 425 puzzles.
Tried by fire
Tried in a lab
Tried and true
Worked on in the lab
Did lab work
No longer green
Taken around the track
Took for a trial run
Known to be in working order
Like a Car and Driver car
TEST as a verb:
1. (test, prove, try, try out, examine, essay) = put to the test, as for its quality, or give experimental use to; "This approach has been tried with good results"; "Test this recipe"
2. (screen, test) = test or examine for the presence of disease or infection; "screen the blood for the HIV virus"
3. (quiz, test) = examine someone's knowledge of something; "The teacher tests us every week"; "We got quizzed on French irregular verbs"
4. show a certain characteristic when tested; "He tested positive for HIV"
5. achieve a certain score or rating on a test; "She tested high on the LSAT and was admitted to all the good law schools"
6. determine the presence or properties of (a substance)
7. undergo a test; "She doesn't test well"
TESTED as an adjective:
1. (tested, tried, well-tried) = tested and proved useful or correct; "a tested method"
2. (tested, time-tested, tried, tried and true) = tested and proved to be reliable