Quite right to sound interested in the company you want to join. My boss actually asked me at the interview 'do you know what we manufacture', I knew and said so, and thought it was a strange question, then he said 'believe me, some people think we make mars bars'. He obviously meant that some people turn up not having researched the company, so my advice would be to go on their website and get some background, think of a couple of questions about the company.
Ask if they have a job description to show you - that would be great to see what's listed.
I would also wear a suit, if you have one, you do need to look professional at the interview (or borrow one from a friend?).
If if it's quite a drive and it gets hot in the car, I now keep some little individual deodorant wipes. I used them last night as I drove in the heat for 1.5 hrs and went straight to the bathroom when I arrived to use them!!!
All the best of luck

Bea