I wonder how HMRC deals with the issue where the driver is able bodied and the non driving passenger is disabled, all the disabled passenger needs is space for a wheelchair so no vehicle adaptions are required?
Probably comes under 3.4 (3rd paragraph):
3.4 Individuals that may purchase an adapted vehicle on behalf of a disabled wheelchair user
HMRC acknowledges that in some circumstances a disabled wheelchair user may be unable to purchase or drive a motor vehicle themselves, although the sale of an adapted vehicle to a person connected to them would directly benefit the disabled wheelchair user’s mobility. Provided that the purchase is primarily for the domestic or personal use of the disabled wheelchair user rather than the personal use of the connected person and that all the qualifying conditions are met, zero rating can be allowed.Where an individual has been nominated by a disabled wheelchair user to be their representative to purchase a vehicle on their behalf, we would expect that the individual has a close relationship to the wheelchair user (for example, parent, son, daughter or carer) and that they live within a reasonable distance of the wheelchair user’s home. Such factors help support the position that the vehicle is for the wheelchair user’s personal and domestic use.
Adaptations to the motor vehicle must be permanent and substantial and be designed to meet the specific needs of the disabled wheelchair user, to enable them to travel in it, by entering the vehicle or to enter and drive it. If only minor changes to the vehicle are needed for the disabled person to enter or enter and drive it, then the purchase of the car will not qualify for zero rating although the adaptations may. See guidance at section 10.
No adaptions = no VAT relief