When Hasbro launched the Generation Two line in 1993, the Transformers franchise had been lying dormant in the US for a couple of years. With steep competition from other toylines and the resurging video game industry, Hasbro had doubts as to whether a new Transformers line could possibly be successful, and they apparently hedged their bets by starting out almost entirely on reused molds and a recycled 1980s cartoon for publicity. Hubcap is one of four "Mini-Vehicles" whose molds had originally been used between 1984 and 1986. Of these four, Hubcap was the most recent, being a 1986 remold of 1984's Cliffjumper.
Many years ago, I wrote a post that I called "Cliffjumper's Identity Crisis." In it, I detailed how most Cliffjumper toys of the time were simply repainted Bumblebees, despite this not being Cliffjumper's original status. While I'm pleased to say that Cliffjumper occasionally (if still not often) breaks out of that rut these days, I now believe that I neglected to cite an even earlier point of Cliffjumper identity-confusion (the 1984/85 "red Bumblebee" mentioned in that article notwithstanding) by not mentioning Hubcap.
Even before the original toyline was finished, in the late 80s, while Hasbro was offering older toys as mail-in offers for "Robot Points," a couple of flyers were released offering "Cliffjumper" to kids willing to send in a few dollars and clipped-out points. No doubt they were disappointed to get the yellow Hubcap toy (as Hubcap was in G1) instead of the red Cliffjumper they expected! Eagle-eyed fans might have noticed that the images on the pamphlets were of Hubcap, but even so....
Fast-forward to Generation Two. Some fans believe that, when G2 was being created, Hasbro intended to offer Cliffjumper, but no longer had access to the Cliffjumper mold, instead having only the version modified to create Hubcap. This may or may not have been the case, and indeed would certainly be consistent with the mail-in offer mix-up. But if so, then the company Fun4All would have had to recreate the Cliffjumper mold for the keychain they produced in 2001. This isn't impossible, but it would almost certainly have seemed an unnecessary stretch of their resources. Either way, the fact that Generation Two Hubcap used a red coloration—the color typically associated with Cliffjumper—instead of Hubcap's original yellow (which undoubtedly would have made the toy too similar to the simultaneously-available Generation Two Bumblebee for Hasbro's comfort) meant that G2 Hubcap would inevitably be confused with Cliffjumper for years to come.
If you ever see a "G2 Cliffjumper" on eBay, don't be fooled. No such toy exists. They're almost certainly offering Hubcap. You can tell it's the Hubcap mold (as opposed to the Cliffjumper version) by the shape of the head (fairly squarish, and lacking Cliffjumper's distinctive horns) and the lowered spoiler in back (Cliffjumper's sticks up creating vertical a point in back). You can see pictures of Cliffjumper here for reference.