Chuck House: Here are my observations after looking at lots of original cars. It appears complicated but there is a general rule (and due to the many different combinations of interior/exterior color and customer options, there can always be exceptions to the general rule!).
On A cars the garnish rails are painted and should approximately match the dashboard top color vinyl. However the dash top color is not always obvious and very often was different than the rest of the upholstery color. The key seems to be whether the upholstery color was light or dark. Darker upholstery had a matching dash top and the garnish rails approximately matched (although usually a darker shade, hence the "complimentary color". Red is an example of this). However, if the upholstery was light, say tan or light grey and the car a darker color, the dash top was a dark color complimentary to the car's color and the garnish rails were painted the color of the car.
I'm sure there are variants to this however the overriding rule seems to be that the factory did not use light colored upholstery on the dash top pad as it would increase glare in the glass when driving and the garnish rail color is linked to the dash top color.
As a specific example, red upholstery in T2 cars had a red dash top and garnish rails painted in a complementary red color, usually a shade darker red than the upholstery.
Here's another example. There was a cream upholstery color for Speedsters, it was call Acella Bast. However when used, the top of the dash was usually a color complimentary to the exterior which was a darker color. Below is an early Speedster with this upholstery. It is restored but is done as original. Notice the top of the dash is blue. The padded dash strips always match the garnish rail color. The rest of the interior was Acella Bast (really a light straw color).
The photo below is another unusual original Acella Bast interior which "experts" would say shouldn't have been done in '57 but was. Note how the dash top is a darker blue than the body color.
[Editor: the photo below shows a piece of original Acella Blast. Photo provided courtesy of Don Zingg, who says that the "original material had a fine brown pattern printed over solid light beige background. Exposure to sunlight and weather fades the printed pattern and darkens the beige background color. Most aged samples look like the color of bamboo or straw."
Brett Johnson: I've also been working on Jim Kellogg's book revision and came across the often argued topic of what color the garnish rails on top of the doors (and under quarter windows on coupes) were. This also pertains to dashboard colors in 1956 and earlier cars, so here goes.
Early on it likely became obvious that light colors on dashboards reflected badly on the windshield in certain conditions. I have no proof that at some point the dashboards became a complimentary dark color to go with the interior — it may have been from day one. Unfortunately, many of these cars have been updated when they were restored/repainted to reflect the 356A and later circumstance where the dashboard matched the exterior color — but more about that later.
The first cars had garnish rails made of wood and while researching what to do for #5142 Doug McCombs noted that original Gläser ones that he had seen were lightly tinted to approximate the upholstery color and we added red tint. He said he had seen blue tint in other examples of original wood. Since #5142 was a dark color and there were traces of original paint, we painted the dashboard Bordeaux Red (dark purply red) to match the rest of the car. Interestingly, the car as purchased (and apparently as it was in 1964 when advertised in Panorama) was bright red with a white dashboard — yuk!
When the Model 52 was introduced in March of 1952 the wood was replaced by steel. At this point they were painted to match the dashboard in a generally dark color that complimented the upholstery. My 1955 coupe has a dark blue metallic color and originally had light gray vinyl upholstery. The exterior color is Adria Blue Metallic, which is a light silvery blue.
The factory provided 1956 color listing implies that there were cars built with dashboards, which did not match the exterior color, but I have never seen one. Unlike earlier cars, these tend to be light colors, probably since the padded top was a dark color. I suspect it didn't take very many attempts, before the paint shop dictated that the 356A with its non-removable dash was a pain to paint with a non-matching color.
The garnish rails on these cars through the end of the T5 356Bs were normally a color similar to the door panel upholstery color, if not a bit darker. This color was also used on the inside of the windshield frame on cabriolets.
The exception to the above stuff was the removable windshield cars: Speedsters, Convertible Ds and Roadsters. These had upholstered rails as did all T6 cars. Upholstery matched the door panels.
Alan Hall: My '59 cabriolet was (and still is) Meissen Blue with a tan interior. The dash top was and is a darker reddish brown vinyl and the garnish rails and inside windshield frame were painted to match the dash top.
Alan Klingen: My father's '56 356A coupe is unrestored and has Graphite Metallic paint, red upholstery, Graphite Metallic granish rails, and a gray dash pad. By chassis number it is the 47th 356A built, so it was built very early in A production.
Barry Brisco: My ivory/brown 59 coupe has its original light brown upholstery on the door panels, rear seats, and rear quarter panels. The back side of the garnish rails show quite a bit of old overspray of the original much darker brown garnish rail paint color. After I bought the car in 2005 ago I had the rails repainted to match that color, as a previous owner (not the original owner) had painted them ivory to match the exterior paint. Below is a photo showing the garnish rails painted their correct, original, color.