If the child has to use a wheelchair to move around, we must seek a vehicle that can be adapted to their needs. Since there are no vehicles that come from factory already adapted, with a few exceptions, the most common thing is modified vehicles in which the rear space has a modification to accommodate the child in the wheelchair.
To achieve this, large minivans and vans in their passenger variants are normally used as a basis. Some models are more appropriate than others for the workshops to perform the proper modifications. An adequate space and regular shapes make the adjustments easier and more satisfying.
As they leave the factory in their standard version, these vehicles have an interior floor that is too high to place a ramp and enter without much effort. Therefore the interiors must be modified, creating an almost handcrafted recess that will be the space where the wheelchair will go, some 20 centimeters lower than the rest of the floor.
Basically, to do this, the part of the floor to be lowered must be removed and replaced with a structure that maintains the same resistance and torsion properties. The stability of the vehicle must not be compromised, so this type of modification must be performed by experienced and duly approved personnel.
With the recess made, it must be properly welded and finished so that the compartment is as strong as it was when leaving factory. The hatchback or tailgate must include the corresponding lower part of the bumper so that access is through a completely level area.
And now that we have a lowered floor, it is time to install a system to lift the wheelchair. There are several ways: you can use a typical manual deployment ramp, a heavier ramp with electric/hydraulic drive, a lifting platform or a crane.
Whatever the system, it should be the one best suited to our needs, taking into account the capabilities of those who help the child get on and off the vehicle, the type of wheelchair (normal or electric) and the weight that the access system has to support.
Once the chair in place, the ramp/crane/platform must hold it firmly without any danger to the child or to any of the occupants due to movements while the vehicle is in motion. But you also have to provide, either in the floor of the recess or attached to the structure of the vehicle, anchors to secure the chair and keep it in place through the bumps and curves.
But why are vehicle adaptations so expensive?
Besides being labor intensive, adaptations can be expensive because of all the legal processes to be followed. It is mandatory for any modification to be approved. In fact, if we do not have all modifications approved, the direct consequence is that our vehicle will not pass the Vehicle Inspection (ITV) and therefore we can not drive it, nor insure it properly nor transfer it in case we decide to sell it.
To get a modification approved, we must go to ITV and pass the corresponding inspection providing a range of documentation required to get approval. We must have a technical project and a final completion certificate issued by the workshop that undertook the work, a report showing the parts used in the modification (make, model and reference), a report of conformity endorsed by a laboratory authorized by the industry, a technical project endorsed by the association of engineers and photos of the vehicle.
All this means that modifications cannot be done by just anyone, or just any way. They have to be well done and have to pass an approval process. And more, because if the modification that the manufacturer does is using a system that has to be mounted directly, it is possible that to get their commercialization approved crash or destruction tests may be required to verify that it is safe.
This process makes the cost of commercializing each adaptation soar. In the end we have to add not only the cost of manufacture and installation, but also the planning, development, construction and all expenses related to the approval process. However, any cost is less than the risk posed by the consequences of an accident.