After breaking everything and putting it back together, I've released version 0.12 of the Carbon Diet site. This version has a great new vehicle emissions algorithm in it, as well as a huge amount of behind-the-scenes hacking, fixing code rot and getting ready for new features.
The vehicle algorithm has changed, so you will probably notice a difference in your graphs. The old method used to assume that you only fill up your car when empty, so the amount you burnt since you last filled up is the amount you filled up with last time. That's not actually very realistic; it's much better to assume that you fill your car full every time, and that the amount you *just bought* is what you've burnt since your last fillup. Hopefully this will even out some of your graphs and give you better results. Huge thanks to Paul at http://www.co2list.com/ for the suggestion.
You might also notice that many of the URLs have changed. I've learned a lot since the site first started 3 years ago, and have been trying to bring it up to date with current best practise, and get a solid foundation to build more features on in the future.
Hope you like it, anyway!