The survey, commissioned by Calor Gas, found wild fluctuations in fleet managers's opinions of LPG.
Although 60% said they might consider converting company cars in the future, 40% said they did not believe it was currently possible.
And there is widespread ignorance about the fuel's availability.
A third think there are fewer than 300 forecourts selling LPG in the UK, despite massive publicity recently to celebrate the opening of the 1,000th forecourt.
Calor's Paul Riding said: 'Many of the fleet managers we spoke to thought they knew about alternative fuels, but this was not reflected in the answers to other questions.
'For example, only 16% knew that in fact there are more than 1,000 retail refuelling outlets in the UK.
'Nearly a fifth of respondents also stated the cost of conversion was a disadvantage. However, with a Powershift grant and the fact that LPG retails at around half the cost of diesel or petrol, the average company car driver can recoup this cost in less than a year.'
In the survey, carried out in April, 6% thought electricity was the most likely alternative to petrol and diesel, with 4% going for CNG and 3% for hydrogen.
Nine Puntos, converted to run on gas by Cardiff and Bridgend-based Enerjen Future Fuels, are being put into service by the Vale of Glamorgan Council.
The cars were supplied by Victoria Park Motors of Cardiff and compared with the standard petrol cars offer cuts in carbon dioxide emissions of 16%.
The council is currently considering future alternative fuel options and has also been running hybrid petrol/electric demonstrators for evaluation.
What fleet managers think –
When asked which is the most environmentally friendly? (Rating: 1 greenest – 4 most polluting)