When the Transformers line was being first planned out in the early 1980s, and the decision was made to feature two factions of characters in a battle of good vs. evil, attention was given to choosing alternative modes that made it possible to quickly determine one faction from the other, even if one didn't actually know who the character was or couldn't find the character's faction symbol. Thus, the early Autobots were all ground-based vehicles (cars and trucks), while the early Decepticons were weapons, communications devices, or aerial vehicles. It didn't take long for these lines to blur, and by just the second year of the franchise, we already get our first airplane Autobot: Powerglide.
Besides being one of the earliest Autobots not to be given a ground-based vehicle form, Powerglide was also one of the first Transformers (alongside his fellow 1985 Mini Vehicles) not to have been previously available in some non-Transformers line. I do not know for certain whether Hasbro/Takara created this mold specifically for the Transformers line, or if had been created for another line (the Micro Change line, for example) but shifted to Transformers while the other line declined. Powerglide is unusual among Mini Vehicles in that his vehicle mode actually has a weapon: the tiny cannon at Powerglide's nosecone, consistent with Powerglide's apparent designation (I get this from the TFWiki. I have no eye for this kind of thing, myself!) as an A-10 Thunderbolt II "Warthog."
Powerglide stands out from his early-Transformer colleagues in a couple of other ways, as well. His arms have actual elbows and his shoulders can rotate (enabling a fairly wide amount of articulation), and his head can turn from side to side at the neck. That these features are required to enable Powerglide's transformation in no way diminishes from their importance, and Powerglide stands out despite sharing the same "unifoot" common to most 1985 Mini Vehicles.
As is common to characters of this era, Powerglide has undeniably received better molds as technology has been updated over the years. A side effect of such updates, however, is that one can most likely locate this mold, now nearly 35 years old, for a very reasonable price. Powerglide deserves a space in any Transformer fan's collection.