<human>: I just got through redoing my car insurance.  As part of that redo, the car insurance company offered me the option to purchase the insurance on a monthly or a six-month basis.  I thought to myself: *Hmm, monthly budgeting will be a lot easier and that's how I've been doing it, but let's see what the costs are.*

Monthly Payments: $75.85.  Total is $455.
Lump Sum: $411.

Now you might say: *That's a 10% interest rate.*  You'd be wrong, because you're making payments for only a six month period.  

20%?  No, because you're making payments every month.

The interest rate if you want to breakout Excel and it's handy-dandy XIRR function?

**66%.  Yep.  66%.**

I've been paying it that way for seven years because when I started with car insurance I had no idea how to calculate time value of money and even if I had, where was I going to get the several hundred dollars to pay in lump?  

Don't be like me, be smart.  Pay it in lump if you can or pay it with something that at least charges less interest than 66%.

Condense the text into a few key points
<bot>: If you want to pay for auto insurance on a monthly basis, it might be cheaper to just put the balance on your credit card and do it that way.