Secondary controls
If you can’t operate the secondary controls whilst simultaneously controlling the steering……..
It is essential that the secondary controls (indicators, horn, headlamp dip/flash and wipers/washers) can be operated whilst simultaneously maintaining control of the steering.
If you have restricted use to one of your arms and are steering with the aid of a steering ball using the stronger arm, it may be possible to use the weak arm to operate the standard indicator stalk. An indicator extension can be fitted to make it easier to reach or to allow it to be operated by the right hand, see – Indicator cross over extension video
If you cannot reach for or operate the indicator with your weak arm you could consider using a remote secondary control system, operated from a keypad attached to a steering ball, this allows for both the steering and the secondary controls to be operated with one hand.
There are a variety of different manufacturers of remote secondary control systems some with keypads attached to steering balls and some with an integral keypad that forms part of a “handle” which is used to turn the steering. These systems are normally fitted with a quick release clamp to allow them to be quickly and easily removed and refitted as and when necessary. For details see:
Lodgesons secondary control video
If there is limited use in the weak arm but finger movement is good it may be possible to mount the keypad on the armrest or on the central console so it can be operated separately from the steering.
Lodgeson Mini Keypad
Bever 8 button keypad
For those people with more restricted finger function the secondary controls can be operated from a single button controlling a “bleeper” system, this button could be operated by the driver’s elbow, knee, or head.
Elbow operated bleeper 
Head operated bleeper
Having a higher spec car with as many automatically operated controls as possible also helps – rain sensing wipers, light sensing headlamps, automatic main/dipped beam and voice activated heating/demist systems are often available as standard features or options on even fairly basic cars today.