Presumably, because Lexus are petrol injection, when converted they start and run on LPG (am I correct in this assumption?).
I cannot access the PowerShift website at present, but seem to remember that cars that have to start on petrol, such as conventional carburettor models do not qualify for congestion charge exemption.
I am not planning to use my car in London, but if I were, would liaise very carefully with PowerShift and the congestion charge administrators if this formed part of my economic calculation. There may be obscure parts of this legislation for example an emissions test may be required under certain circumstances.
Has anyone with a Lexus gained this exemption, what did they have to do to get it?