And here I thought I knew about all there is to know about Schaukelwagens. Turns out that not all Schaukelwagens are old. The Schaukelwagen did go into production soon after it was designed [in 1950 by Hans Brockhage and Erwin Andra] but it didn't stay in production long. Something about being a bombed out, broke country recovering from the war apparently put a damper on high-design, high-priced race car-to-rocking toy combos market.
Anyway, DT commenter Ray pointed out that the German discount retailer Manufactum put the Schaukelwagen back into production--with Brockhage's blessing--around 1998. I found mentions of them as late as 2002, but apparently the Schaukelwagen was still too expensive [around EUR450].
There is even a modern Schaukelwagen for sale at the moment, at Retro-Nova, a Berlin vintage design shop. I emailed some questions, and Stefan, one of the owners, sent along this image of their Manufactum Schaukelwagen, which looks fantastic. Stefan said that the reissued rocking racers were basically identical to the vintage models. I'd imagine there has to be a label or tag or something to distinguish them, but otherwise, the only difference is going to be condition. And price. Where a c.1950 Schaukelwagen can run upwards of EUR1000, Retro-Nova's modern version is only 300 euros. Practically free!
Retro-Nova - Varia [retro-nova.de]