I don't think any of them are, really, but many of the ones based on larger figures seem a lot smaller by comparison, such as Powermaster Optimus Prime, Optimus Primal, and Star Saber.
I have a few. Would love to get them properly painted: Powermaster Optimus Prime Triggerhappy Rippersnapper Brainstorm Hot Rod Crosshairs I'll have to get them out of storage but I think I have Slugslinger and Chromedome as well.
I believe Kabaya Magnus can hold WST cars. I got a factory case from BBTS, but I don't know if they're still in stock at the moment.