Use it for every tank of gas, for each of my vehicles, without fail. It doesn't just do the math, it also tracks over time, shows charts & graphs, converts between metric and US measurements (no Imperial yet though), and allows you to compare real world mileage among vehicles.
It was a great...
"The service will be available starting at $39.95 monthly, plus GST, PST, and eco recovery fee. Only shows approved by CRTC will be available on the Canadian service. No local sports will be streamed."
Go hit lowendmac.com or everymac.com and look up the specs. The iMac is worth maybe $40 the others virtually nothing. However that wouldn't stop me from taking them home. I use all kinds of old Macs for Linux servers, print servers, etc.