Time for an off-site garage. Keep the car in one of those storage units for the first month or two. He can drive his beater to the unit and pick up his new car, then drop it off at night and drive home in the beater. After a couple of months, the kids can "surprise" him with a new - used car.
And they'll have a good story to tell the grandkids after mom has been committed.
I rented a storage unit last year and met a guy that kept his NSX and Hayabusa in one. Told me it was safer than his condo parking lot. A couple hundred a month and 24 hour access.
