I was entering the information in with returns after each item. Didn't get from the instructions that you need to enter it with spaces as delimiters. When I entered it as a string with spaces between the values it worked just fine.
Yeah, that error message is just our generic "this wasn't formatted right" message. We use "[Miles] [Price] [Gallons]" in error messages even if your vehicle uses odometer tracking or if you fuel in litres. We'd like to remind about the whole MPG shortcut which is an easy way to remember [distance] [price] [fuel volume].
Glad you got it figured out. I added a line about using a space to separate each item in the FAQ.