Mr. Tim Sanford at the Transport, Infrastructure and Communities Committee

I believe in the taxicab market a lot of it had to do with the lower cost on the actual conversion of the vehicles themselves. Propane was a little bit lower in cost.

The range of propane was probably a bit of an advantage for the vehicles. Propane is a little bit more costly than natural gas, but there's a little more range and availability of propane stations throughout the city of London.