Who can answer – ultimately a judge, or at the very least a first tier tax tribunal panel. There’s not currently much case law on the matter, and very few cases that have set a precident
HMRC and Motability may have a view, which may sometimes be right. Many on here will also have a view, that may also sometimes be right 😉
However the key point for the adaptions themselves in the actual legal text is the phrase substantially and permanently adapted which raises the question of who/how are substantially and permanently adapted defined, especially as the adaptions are removed at the end of the lease for onward sale where possible.
Steering wheel balls, and Lynx hand accelerator controls have both been deemed not to be permanent as they are easily removable by the end-user / car hire technician and the car can be used immediately after removal without any further modifications.
Wheelchair ramps, for WAV conversions certainly do. As do tillers and joysticks that remove the steering wheels.
Bolted onto the car devices like person-hoists and equipment stowage hoists have been approved for some of our clients in the past by HMRC.
So pondering a left-foot accelerator … that might depending on the type.
If it’s one that is electrically connected, then probably;
if it requires the manufacturer’s original to be removed, also probably;
If it is clipped onto the original ….. maybe not. Sorry that may not be what you want to read.
But that’s just me pondering on a quiet bank holiday, and without running it past our legal team, HMRC or other party that could offer a ‘professional opinion’
But I return to my original point – there are always legal rights to challenge decisions, and they should always be taken if your adaptations are declined.