I have been developing this habit of using my credit card less and less (each time, I'm actually trying to weigh the benefit of getting a float versus paying by cash). I've never used it for fuel, instead have opted for a smart card from Bharat Petroleum.
The main reason is that I'm quite concerned about credit card fraud. All the devices currently print the entire credit card number along with the expiry date (I think) and other information. As a result, any place that has a copy of this can commit fraud (especially of the online variety).
And, given that more and more places accept credit cards, the penetration levels of possible fraud is increasing at a very high rate.
BTW, here's an article indicating how gangs (including terrorist rings) get credit card information from hotels, petrol pumps, etc and carry on their nefarious activities.
And, how many times has the person at the counter actually verified your signature at the back with what you've put on the bill ? Try and recollect. I've tried my part at educating many of the places that I visit, but it's a hopeless battle :(
IIRC, some of the major players have changed the specifications of the reader machines such that these machines are supposed to print only a few numbers off the entire card. However, those machines are not expected to hit the market in the near future (my vague memory reminds me about something around 2007-2010). Till then, be careful, very careful.
For those of you who use credit cards online, AMEX has a virtual credit card number facility. With this, the system generates a one time credit card number that use for a particular transaction. After that it is invalidated. IIRC, the number of times it could be used could probably be specified by you, but my memory is vague. They provided it free for their American customers. Not sure about other places.
All the best flashing that piece of plastic !!