Condolences for you and your family, Jerry. In due time, slip a photo of your father-in-law in the glove box and take him on a ride..
I do that for my Dad always. I think of him often, especially when riding, I find myself talking to with him, I sometimes 'hear' him talking back.
Memories are wonderful, it's what's left of our loved one's until we meet up again in the hopefully distant future. God bless.