is to run the car on the painted lines on the gymnasium floor. Have the car start straddling the baseline and then push it forward. It should run smoothly straddling the baseline for a good 6-7 feet if it's properly aligned.
If you have access to the track, run it on the track and monitor how many times it rubs the lane guide(s). You can also time it until you get consistently fast ETs, which means it's well-aligned. This is the gold-standard IMO, however, tough to do if you aren't the track-master.
If you find the car isn't tracking well, start with the one front wheel that is touching the floor/track and turn the axle head with a plier (gently!) 1/4 turn then re-run the car. Continue with the 1/4 turns in the same direction until you get it tracking. If there is no difference, go to the back wheels one at a time and perform the same 1/4 turn adjustment until you find the culprit and get it ironed out.