The self service kiosk cannot be used on 2004 and older cars or 2007 and older trucks
Some of the emissions statistics have a self serve option that is cheaper than the standard option. If you can get there early enough, like when it first opens, it may not be crowded. I actually did my emissions when the actual station was closed.
You can actually click on their website and you will see a chart that shows how busy the emission center is on an hour-by-hour basis throughout the day. My guess is that you don't want to go on a Monday or a Friday as those are most likely the busiest days of the week so mid-week would be best. Then, want you to decide which day you want to go simply go to the MVA emissions site you were going to and look at their chart of how busy the center usually is during the day.
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