He probably looked to Sasha for comfort and leadership, and now that she is gone no one has stepped into that role for him.
I would spend time in the car when it is not moving and make sure his behavior is good when things are quiet. Then drive down the driveway and around the block is he good then? If not I would put him on the leash in the back seat with someone and help to guide him into better behavior. Do not 'coo' at him and support his insecurity. Instead give him jobs to do - down/stay. You also need to correct the crying. Let him know you don't like it. Think of a child who whines in the car. You are going to correct him but you are also going to try to give him things to do to keep his mind off of his worries. Create a new dynamic for car rides.
We worked with a GSD who literally screamed when she was in the car with her parents. SCREAMED!!!!!!!
I would work the dog for a few minutes outside of the car to earn some leadership and when I got in the car the dog stopped instantly. I never had to even discuss it with her. She just needed to know that someone else would keep her safe and be there for her.