A fuel conservation technology should not consume too much energy or money to adapt that technology.
That technology should not cause pollution, and should not release any green house gases etc.
Fuel conservation technology should be economical, and it should be affordable by people.
Fuel conservation technology must be widely available.
The habits for fuel conservation, should not cause inconvenience to people. It should not be time consuming, costly. Any fuel saving habit should not lead to over spending on some other energy. Use of public transport, shared transport should be available.
What is important is that people should deliberately remember that fuel saving is important.