No matter how hard we try -- no matter how many employees we've interviewed, much less hired -- we all still make hiring mistakes.

It's understandable. During the job interview, every candidate is at their best: they're up, engaged, and "on." Plus, skill is fairly easy to assess compared to less tangible qualities.

According to one study, only 11 percent of new hires who failed in the first 18 months did so due to deficiencies in technical skills. The majority washed out due to problems with motivation, an unwillingness to be coached, or a lack of emotional intelligence.

That's why many people add their own small twist to the interview process. One I liked to use was talking to the receptionist afterward, since what candidates do while they're waiting in your lobby can tell you a lot. (A nice guy in the lobby may not be a nice guy on the job, but a jerk in the lobby will always be a jerk on the job.)

Or I would ask another employee to conduct the plant tour, which was a sometimes great way to find out what the candidate was really thinking. (You'd be surprised what people will say or ask when their guard is down.)

And then there's the Chad Knaus "car test" (my quotation marks.)

Chad is a six-time NASCAR Sprint Cup champion crew chief for the #48 Chevrolet driven by Jimmie Johnson. (The team is owned by Hendrick Motorsports; if you aren't familiar with NASCAR, a crew chief at Hendrick is to auto racing as the manager of the Yankees is to baseball or the head coach of the Patriots is to football.)

Every candidate takes an emotional intelligence test before the interview. "There is no good or bad result," Chad told me in the team's hauler. "Whether an individual is introverted or extroverted, for example, doesn't affect their ability to do the job. Great teams are made up of all sorts of individuals. What the EI test does do is give me a sense of how to conduct the interview so I can better relate to that person."

After the interview, Chad will sometimes walk with candidates to the parking lot to say good-bye... and to check out their cars.

"I don't care what kind of car they drive," Chad said. "Old, new, expensive, inexpensive... none of that matters at all. But I do care about whether they take care of their car. If food wrappers are lying on the seats... if the car isn't clean and well maintained... I figure if you don't take good care of your stuff, you aren't going to take good care of ours."

Is Chad's car test the only hiring criterion that matters? Of course not -- but it is another tool to evaluate whether a candidate is a good fit for the team and the overall culture of the Hendrick organization.

Think about what matters most in your organization and devise your own way to test for cultural fit. Maybe you'll use a version of the server test. Maybe you'll do what a friend does and see if the candidate pitches in with you to help stack a few boxes at the end of an assembly line. Or maybe you'll run a version of Chad's car test.

Whatever you do, the goal is to learn more about the candidate so you can make a better hiring decision. Think of it as another way for potential hires to show they are a great fit for the position and your business.

Most will shine. Some will not.

Either way, you'll be able to make a better hiring decision -- and isn't that the whole idea?