Posts 18-21of the disABILITIES FAQs thread have up to date information about ride access. You can find that thread near the top of this board or follow the link in my signature.
The FAQ is a great first resource but note that it was prepared many years ago and some of the rides that are on the list no longer exist (and some new ones may not be covered). I believe the Test Track car is similar to the car at Radiator Springs in California and while it is a modified car my issue was getting out because of hip replacement and knees--even with the modified car--if your Dad has help this might be do-able. Slinky Dog Dash and Alien Flying Saucers should be ok--you should be able to take him directly to the car with the wheelchair but he will need to transfer.
Actually, the FAQs thread was
started many years ago, but is regularly updated.
The date of the regional post can’t change, so if I originally wrote it in 2004, that’s the date at the top of the post. But, it may have been edited many times between then and now.
Some things haven’t changed (ie, the Disney Magical Express bus info or pool info) and some (post 3!) I have not had time to do much to since this is a volunteer gig and I have to work on it during my free time.
The 4 posts about ride access (posts 18-21) are looked at for updates after every trip my family takes and as I find out about things in other ways. We go twice a year for 14-16 days. I also remove things that are no longer in operation. For the example, I just read that Primeval Whirl at AK was made seasonal and added that information to the AK post.
I added Slinky Dog Dash and Alien Flying Saucers after we tried them out on our last trip in a March/April 2019
Test track does not have a modified vehicle it does have an alternative loading section. My daughter loads upstairs at the seatbelt check because she can pull her chair up to the car. If you load downstairs (regular loading area)you have to step down into car
Just what I was going to say.
I would compare it to going over the side of a fairly high bathtub. So, better than stepping down into the car at the regular boarding area, but not necessarily easy.