You can check them with an Ohm meter.
If digital, put the selector on 20M
If it is still in the car make sure the lead is disconnected.
To charge it put the black lead to the case and the red lead on the condenser lead. You should see some movement of the meter. When it stops it will be charged. Now switch the leads and put the red lead on the case and the black lead on the condenser lead. You should see the Ohmeter go up in a couple of steps and then go back down as the condenser discharges.
At one time I remember testing small engine ones by charging them on a battery and then grounding them. If they sparked they were good. Not sure if that’s good for the condenser though. You could likely see a jump with a voltmeter if it was charged as well.
Just off the top of my head, since you are looking for a very quick measurement, that automatic selection meter might not be the best choice. I'm thinking that the meter needs a longer "signal" (for want of a better word) from whatever you're measuring to select the type of measurement.
That's just a quick observation that may not be worth anything... But a check with another meter would be my first option.
FWIW, I buy those cheap Harbor Fright meters, make sure that they work and toss them in my trunk tool box. They are perfect for a back up or "sanity check" as it was referred to back in my working days.
Get an analog meter. Get a GOOD one if you can afford to. Simpson 260s are STILL THE SHIT, accept no substitutes. You can find used ones for $50, which should work if the vendor is decent.
You CAN get a specialized digital meter which will read capacitance. OR, if you have a fixed current source, you can indeed estimate capacitance using a little Physics 103: Q=CV. Q = It, ergo, It/V = C. Soooo, watching your Simpson 260's jeweled meter pointer slowly rise through a known resistor at 12VDC, you can time when it reaches full charge, Q. Now I = V/R, so, plugging that in to solve for C, we get t/R = C. There you have the Answer! Use a known R, at 12V, and make it a nice big one, place it in between your 12VDC source and the capacitor, watch your meter reach maximum V, (12V) and clock it carefully. Then divide your result by R. I advise you use an R no less than 10kOhms.