There's no icon under basic stats or recent fuel ups to import a CSV file as specified in your FAQ.
Fuelly can import existing fuel-up data you have. You need to format it in a plain text CSV file. Take a look at Importing Your Data Into Fuelly for details about the CSV format.
Once you have your fuel-up data ready to import, you can find the import link on your vehicle profile page. Look for the Import Fuel-ups link under Basic Stats or the import icon under your recent fuel-ups: Import Fuel-ups for this car
posted on August 26, 2008
Look on your car's page immediately below the "Log Book" section. There are three icons immediately to the left of the "Badges" link -- RSS Feed, Export Fuel-Ups, Import Fuel-Ups. The Import Fuel-Ups icon looks like a little spreadsheet. You should see the description for each icon as you roll over it.