My friend went to a car repair garage with this test and failed. But he went to emission test center just after a few days, then passed! (He also found that there has a speed limit for the test but the garage used much higher speed for test and don't show the speed on the test paper, then, gave him $1000 quotation for repair!)
If your car is old (thus may or may not pass), you'd better to fill up with a full tank of premium (#91) gasoline, drive 10+km highway (in no-congestion situatiion), then go for emission test appointment. Good luck.