Gave a young lady a refresher lesson yesterday. She passed her test two weeks ago with another instructor, got herself a little car but can't drive it. It keeps stalling. 
Her friend my pupil introduced us after she told me the story, I explained she had probably had lesson in a diesel car and the instructor to make live easier for him had taught her to start without gas. My highly experienced pupil (six hours),  tried to help her by telling her she had to use the gas pedal. She did  a bit too hard, but got lucky.
Yesterday we spent an hour stopping and staring, even found a little hill and she ended the lesson happy and confident.
I have a petrol car because of this, but why do instructors with diesel not teach them to use the gas?