Safety critical subsystems (steering and brakes) should always have manual overrides of some sort.
Also why do we need DBW acceleration control? The old traditional acceleration control doesn't add much weight or cost.
Only add DBW for fuel savings, power windows, etc. Items where they do not cause safety problems.
My vote is as follows:
DBW: Fuel saving, power windows, door locks, handless phone service, handless music/stereo control, tire pressure monitor, fluid monitors (fuel, oil, hydraulic, radiator, etc.). Any other function that does not directly or immediately affect safety.
No DBW (or at least manual overrides): Steering, Brakes, Accelerator control
Joy stick control is enjoyable in place of the steering wheel.Initially a joystick and a steering wheel which could be retracted a touch of a button in the joy stick can be provided.In case if the joystick fails the steering wheel will come out and the user can control with the steering wheel.
My experience in vehicle development is littered with electronic "assist" systems that endanger the driver and passengers by causing the car to behave in an unexpected way. For example, the traction control system of the 5th generation Corvette nearly killed me. Went to pull into traffic where there was a little loose gravel. TC saw a bit of wheel slip and simply shut down the power, leaving us dead in the path of an approaching truck. Common situation that would have posed no threat ordinarily- made nearly lethal by the assumption of an electronic system. Similarly, during developoment of the Prowler, the auto-stick tried repeatedly to wreck us. Downshifted approaching the S-curves at the tech center. Tranny won't shift, won't shift... Finally I have to get into the brakes -late. Entering the curve, the computer decides to downshift, of course snaps the rear end out, putting us sideways. In this case, simply a little extra fun- correct & verify on the next lap. Never had the ppportunity to drive a production unit. Can't say if it was ever corrected. My point is that these systems cause a car to behave unpredictably in the hands of an engaged, skilled drive. As a veteran automotive electronics engineer and skilled driver, first thing I do is turn off any computer assistance that can be turned off. I'll trust 850,000 miles of safe experience. Unfortunately, far too many "drivers" only want an appliance. When we can put them into a fully automated car, or better yet mass transit, then I'll feel safer...
I think one point most of you are forgetting is the tactile feedback of the wheel. It lets me know how hard I am turning. There is none of that in a DBW system. Its one of the reasons fans of racing games always go back to the steering wheel. Its just more robust(tolerant to noise if you will) I know I won't use a joystick for a car it just wouldn't feel as controlled.
Drive By Wire (DBW) to reduce weight and cost are fine. But the more DBW, then the more required yearly inspections we will need to ensure vehicle safety - especially on older cars. We already have emission inspections. If we have more DBW then we will have to mandate DBW inspections as well. Not a big deal if we have it at the same time as the yearly emission inspection. Of course the car makers will need to provide test portals and procedures so that the inspectors can thoroughly test the safety critical DBW elements.
If you folks think that the older drivers can not handle a vehicle with a joy stick, then you should drop by a Senior Center with assisted living. Lots of the scooters and power chairs are controlled by joy sticks and these seniors are doing pretty well with them.
There is a valid reason for having a steering wheel, inertia. when your driver's side tire hits an obstacle this unbalanced force can cause the steering angle to change. the forces restraining this are due mostly to the inertia from the steering wheel. this inertia is due to the fact that 1 turn of the steering wheel produces perhaps 1/8 of a turn of the tire about it's steering axis. this 8 to 1 advantage is squared to get the unit correct, so the steering wheel comes out with the majority of inertia. without this wheel the electric power steering would need to generate greater correcting force.