Your profile says "I am caring for my mother Mary, who is 97 years old, living at home with age-related decline, alzheimer's / dementia, anxiety, broken hip, urinary tract infection, and vision problems." And your husband also has dementia?
Put duct tape over the inside of the door handle so that he cannot use it. That way, the passenger door can only be opened from the outside.
I've heard of this duct tape idea...I'd get a color that matches or blends so it becomes more invisible. At least you'll know they are going to attempt it with some warning if the tape has to come off first!
Do you have kiddi locks on the doors or driver operated central locking? If not for front passenger door but on rear then maybe he has to travel in the rear from now on.
You can use the child locks and make him sit in the back seat. You can also get a mechanic to disable the lock mechanism on the passenger side so that it only opens from the outside. We have done both.
Certainly find a way to disable the handle inside (if the car is newer there should be a "master" locking mechanism - I think the child-proof locking is only in the back.) Duct tape can work, maybe... Unsightly and may be difficult to remove it all later, but the handle itself could be removed.
"...almost impossible to open a car door traveling at highway speeds." Not to be totally flip, but almost only counts in horseshoes, hand grenades and nuclear weapons.... No point in testing it out...
The only thing you can do, is to completely remove the handle from all passenger doors as we have with police vehicles. otherwise you'll need to pull your power locks fuse, which removes your driver ability to lock that suicide door. Front passenger doors usually don't have the manual childlocking mechanism, at least that's been true for all of my personal Swedish imports, your local dealership might have more answers, including the ability to pull the correct wire to disable his use of his door's power lock...yet he can pull that lock manually too; he's old so he'll yank it up to unlock that door. Police vehicles don't have that manual lock visible or accessible. your dealership can remove it. A 5 point harness seatbelt is another option in the front passenger seat. BEST = shoving a hostile passenger into the backseat as is done in law enforcement and taxis, that's is statistically the safest, but you must remove all handles, that open all backseat doors. and you must manually flip the childlocking mechanism And you might eventually need a cage between the front and back areas to keep him from attacking you while driving; consider him a hostile passenger, protect him and protect yourself. I missed seeing the type of vehicle in which he does this; it sounds small since you wrote that his equipment sits in your back seat,no trunk? that "roller" is secondary and should be considered after you secure your living beings. His roller will fit on an exterior bike-rack. Have you considered purchasing an old crown vic, from a police auction??
Child locks! This happened to me with a kid who had autism. He opened the doors while I was driving. Terrified me! I always had the child locks on after that incident.
His mom said he did that occasionally. Well, I wish she had warned me about it. She always sat in the backseat with him so fortunately she grabbed him and I immediately put the child locks on. It’s scary!
Newer cars are equipped so that only the driver CONTROLS ALL DOOR LOCKS. The driver should lock the doors immediately when his/her passengers are seated and even before buckling them in!
Make sure the seat belt is on him and tight so he can't get out. But make sure you have some kind of a locking system that YOU control from the driver's side so he cannot open his door. And if he tries again, DO NOT PUT HIM IN YOUR CAR. Find another solution.
I also went the duct tape route on front passenger door inside handle. It works. Not a big deal to going around the car to open it from the outside. In a true emergency put the window down and reach over with your hand and pull the latch on the outside. Know this isn't a one hundred percent ideal solution, but we only take short trips.
Move him to the back seat. The back doors have child locks on them. When you open the door look at the side panel. It's a little black switch that moves up and down. Once it's locked the only way the door will open is from the outside. There is also a seat belt lock you can buy that will keep in seated but it doesn't solve the issue of opening the door, especially if he's in the front. Look on Amazon.
Put duct tape over the inside of the door handle so that he cannot use it. That way, the passenger door can only be opened from the outside.
I like faeriefiles idea - talk to your mechanic about disabling the locking/unlocking mechanism.
Also, it is almost impossible to open a car door traveling at highway speeds.
"...almost impossible to open a car door traveling at highway speeds." Not to be totally flip, but almost only counts in horseshoes, hand grenades and nuclear weapons.... No point in testing it out...
His mom said he did that occasionally. Well, I wish she had warned me about it. She always sat in the backseat with him so fortunately she grabbed him and I immediately put the child locks on. It’s scary!
If you have a master lock on the driver side maybe that will work.
I didn’t have those options are used to have to hold her sleeve. Good luck!
We do this when we have mother riding.