I have had this discussion several times, and answers are always different.
To be exempt from Texas emissions tests, a car must be through 24 years old, according to the state wording.
In 2017, a car made in 1993 will be 24 years old, and going on the 25th year. So 1993 cars are through 24 years old, and should be exempt starting next year.
Yet many people at the state say this car must be another year older to be through 24 years old. But that is not correct.