502 Motorworks is currently auctioning off its second Spyder build on Bring a Trailer [Update 11/3: the $160,000 high bid did not meet reserve]. It is a stunning replica, in all aluminum, of an original 550 late production low-rail car—accurate enough to have received an FIA historic race passport, meaning it is cleared to potentially campaign against real historic race cars including original 550 RS Spyders.

The car, equipped with a Porsche 1500 “Super” pushrod engine, reportedly cost most of $300,000 to build. This puts it in the stratosphere of the replica world. The kind of thing the owner of a real 550 would buy so he’d have something to drive on the road—or the track.

Which is to say, it’s far beyond comparison to my modest home garage effort.

But let’s do it anyway.

It is said—and to my eyes it’s true—that the dead giveaway on older-mold ‘glass Spyders like mine is the shape of the rear fenders. But honestly it’s not super apparent in the above shots. I think it’s more noticeable below.

From directly behind at an adult’s eye level? Not so much, imho.

Even at 3/4 from the rear, the two cars aren’t strikingly different.

Other angles look even more similar. Under the back end:


Under the front valence:

Note that the 502 car’s sway bar appears to be correctly mounted (as the lowest point on the underbody), whereas my car’s is invisible, tucked up between the trailing arms. Make your own judgment about which location is more practical for use on public roads. I think the 502 car uses a thicker-than-stock bar. Mine is the (I believe) period correct 13mm.

Cockpit from driver’s side:

Frankly I like my car’s panel gaps better. And while we do have the full interior treatment, it is only velcro’d in mostly, so it’s easily removable to reveal the aluminum and rivet work underneath.

Even under construction they had similarities in detail:

Cockpit as seen from the other side:

I think the 502 has mine on the pedals. They’re just right; mine are just close. The 502’s shifter is also exactly right, whereas mine is sorta similar. But what’s with the gaps around the frame tubes? I believe they have also mounted the headlight dipper switch a few inches too high.

Frame and firewall.


The 502 car’s underhood game is strong. The fuel tank looks dimensionally close to correct. All the rivets and angled panels and little reinforcement bits appear to be present and accounted for.

I think I might have a more authentic battery hold down though.

And my car’s tank cover is not too far off.

Here’s a shot of The Spyder Factory 99.99% replica of 550-0090. Note the shape of the front edge and the bead line along the outside edges:

Mine, again:

Not everyone knows the tanks are supposed to look a little lumpy, as they were originally hand hammered. The paint on mine is the closest match I could find to proper tern plating, which is basically melted lead. They weren’t painted black originally.

As far as I know, The Spyder Factory is the only restorer/builder that gets this detail right. Most of the original tanks are long gone, replaced by copies made of smooth, flat steel, painted black.

The engine bay is where the 502 car takes liberties. The clam reinforcement piece—an iconic part of the 550 look—did vary quite a bit over the production runs. This car invents what looks like the next evolution.

Mine is thinner, a bit rumpled.

An original, courtesy of

Obviously, my home-built Thunder Ranch kit will never receive an FIA passport. It will never carry a Porsche VIN and is unlikely to ever get a Porsche engine. There’s just no comparing it to a 502 or Spyder Factory car.

Then again…if you saw it parked on a golf course lawn, how quickly would you be able to tell?


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