The post is not so much direct techniques as those will vary by type of roof and upholstery, age, and condition.
Automobile upholstery falls under two basic types that being either true leather or a vinyl pseudo-leather.
The pseudo-leathers (vegan leathers) are synthetic “breathable” leather substitutes, basically are plastic coatings, usually polyurethane on a fibrous base.
They fall under various brand names Naugahyde, Muskin, Ecologic, Calrion, Rexine and more.
This includes diamond tufted vinyl.
Uniroyal provides a PDF on how to care and clean the vinyls such as Naugahyde.
They recommend not using paper towels for cleaning and also advise against using Formula 409, Fantastic, and Armor-All. Basically use a quality vinyl cleaner.
As for leather, the most common type used in automobiles is cow hide, but is not limited to that (deer, goat, antelope…).
Leather is prepared in assorted ways for use, Types being aniline dyed, full grain,split face, top grain, Nubuck… The main concerns on leather is if it has a full aniline dye, what the type it is, and how old.
For basic cleaning (except full aniline dyed) a damp cotton cloth will do for general cleaning. This effort should be done at least twice a year.
Full grain natural finish leather displays the leather grains and these develop a nice patina from use and should be cleaned lightly unless a serious stain occurs. It may have an aniline dye so the damp cloth should be tested in a hidden spot to see if the dye pulls out. If not then the damp wipe for basic care.
Newer cars with true leather seats will have a polyurethane coating, if the coating has not deteriorated then stick with a high quality automotive DEDICATED leather cleaner for short term cleaning. Do not choose a spectrum cleaner that lists leather, vinyl and plastic.
For periodic cleaning (a couple times a year switch to a natural balm dedicated to leather. Make sure it is identified as a healing balm for polyurethane coated leather.
If your seats are showing age and ground in dirt or the polyurethane coating has started wearing then for deep cleaning use a saddle soap cleaner. Verify on the label the saddle soap meats automotive use and is good for the type of leather in your car. TEST in a hidden area to make sure it does not remove dyes or stains and streaks.
Leather needs rehydrated! The regular wiping with a damp cloth will help rehydrate. For dried out seats slowly rehydrate by more frequent damp wipes bringing back the moisture. Do not use products that contain silicones, petroleum distillates, or identify a glossing shining additives.
Older leather in cars (vintage) if they have not been cared for, will need to be cleaned (saddle soap) and rehydrated. They likely did not have a polyurethane coating. It may be likely these had mink oil or neatsfoot oil used as a conditioning, softening and preservative. These oils work very well on older leather.
Corinthian leather. OK, I add this even though it was in Chryslers only starting in the 1970’s and is not a actual type. It is part of the early examples of leather vinyl mix being marketed as a high end fancy leather. But makes a good point that part of the seat may be leather while other parts will be vinyl and each cleaned and handled differently.
Landau or vinyl tops. (and canopy)
Landau, when used in referencing an automobile, generally means a simulated convertible, was based on Landau horse carriage.
Landau tops started out in cars being canvas or leather, but in the 1950’s started the transition to vinyl.
Again the first need to to sort if the top is vinyl or leather. If the top is not cracked or split then clean as you would any other vinyl or leather. For leather roof hydration and protection periods should be increased.
Vinyl you should look for a cleaner/protectant that is directly made for roof with UV protection. Both types can have a re-dye if the fading is too bad. If it is a vinyl top and shows cracking, you may find it is better to replace the top. The process is not extremely complex and achievable by the average car do it yourselfers..
This post is only a view based on years of dealing with cars from very old to new and what I have found works for me. There will always be the idea of a better mouse trap, but in the end they all eat cheese.