Believe me, I've devoted an inordinate amount of time over recent months to checking out all kinds of Google offerings related to disability travel in my quest to find a hire car with left-foot gas. At the last count I'd contacted in excess of 40 rental firms - Italian, British, German, Dutch - plus numerous UK-based help organisations...all without success.
I did locate several companies offering wheelchair-access vehicles. Shamefully, I haven't kept a note of any. Sorry.