Which is a better excuse?

So I started working at a daycare late August, it’s been hard but predictable and I have weekends off. I am also looking for a new job that isn’t so hard on my body. I worked an office job for 7 years and due to boss issues I went to work at the child care facility. I like the people and the kids not the management style. Here’s my situation. I have a job interview for a job I really want next week during my scheduled shift. Do I a tell my current job I have a last minute appointment with a doctor or tell them I have car issues. I know better than to tell them I have a job interview. So which sounds better doctor or car issues.