He moved, as Technical Director, to Daimler-Benz in 1935, but his career was cut short by Pneumonia to which he succumbed, according to at least one report, after a drive in an open-topped car, and as a result of which he died.
His father hoped that he would, in due course, take over the family business, and with that in mind Hans Gustav attended the Realprogymnasium [de] (lower secondary school) in Uerdingen between 1905 and 1911.
[1][2] In 1911, still aged only 17, he accepted a two-year internship at Düsseldorf-Oberkassel with "Rheinischen Aerowerke GmbH",[4] which he had been offered through the mediation of his friend Joseph Dauben (1889–1960) who was already employed as an engineer by the company.
One records that his father became progressively more alarmed by his son's obsession with so dangerous a hobby, meaning that the younger Röhr was obliged to accept "help from strangers".
[4] The maiden flight of Röhr's monoplane took place in November 1913, vigorously applauded by onlookers and, in print, by the "Uerdinger Anzeiger" (local newspaper).
[2] The elements of Röhr's later designs could already be seen in these prototypes, combining lightweight construction techniques in a car intended to appeal to the masses and to be priced accordingly, while incorporating the quality standards normally associated with the luxury end of the market.
[5]) The result of their endeavours was a futuristic underslung chassis frame ("Tiefbettrahmen") using sheet steel and incorporating independent suspension, lightweight construction and, by the time they built their second prototype after moving to Berlin in 1920, hydraulically controlled brakes on all four wheels.
Backed by the deep pockets of his new investor, including an immediate cash injection of 500,000 Marks, on 30 October 1926 a new company, Röhr Auto AG [de; fi; uk], was established.
[6] It quickly became apparent that the factory space at the Ober-Ramstadt was not suitable for high volume production, so Röhr sent his chief construction engineer Joseph Dauben back to the drawing board to adapt their existing prototype as an eight-cylinder car that could be produced in relatively small quantities.
[6][7] The design reflected the experience gained from the prototype vehicles already built, and featured light weight construction using an underslung chassis frame formed from sheet steel.
[6][8] Although its exterior was not particularly remarkable, some of the more astute visitors to the 1928 show stand were impressed by the unusual nature of the chassis, and the design also caught the attention of overseas pundits.
While some admired the novel configuration of the rear swing-axle, more conservative elements simply complained that the car was missing a "proper" (beam) axle at the back.
[8] In order to avoid having to extend the length of the car excessively, the engine block now used a "narrow V" configuration, with the angles of alternating cylinders differing from one another by just 10°.
The listed retail price for the Röhr 8 10/55 was only slightly higher than that for the earlier model, but sales volumes were nevertheless disappointing, with only around 350 cars produced between 1930 and 1933.
With the agreement of creditors Davos-based "Schweizer Holdinggesellschaft für Automobilwerke" a Swiss acquired the company's assets at the foreclosure sale in June 1931.
[9] In or shortly before May 1931 Hans Gustav Röhr joined Adlerwerke AG in Frankfurt as Head of Product Development ("Chefkonstrukteur"), Technical Director and a deputy member of the board.
[1] Adler was a financially challenged but still significant – and, after Röhr joined the company, innovative – motor manufacturer[10] which in terms of unit sales ranked fourth (behind Opel, DKW and Mercedes-Benz) in the German auto-market through most of the 1930s.
The Adler Standard 6 had become a favourite with the German upper middle class and with those taxi operators who thought the similarly sized offerings from Mercedes-Benz slightly over-specified and over-priced.
Even more courageously, Röhr's brief involved designing a front-wheel drive car, following the trend set by the recently presented DKW F1 and Stoewer V 5 [de; pl].
According to at least one source even André Citroën, the man who had introduced assembly-line manufacturing to Europe (and especially to Opel), seriously considered assembling the Adler Trumpf under licence in Paris, before selecting the (financially more perilous) option of creating his own front-wheel drive model.
The cars anticipated European styling trends of the late 1930s, being lower and, with a new all-steel body by Ambi-Budd of Berlin, sleeker than their predecessors: these suddenly looked curiously perpendicular by comparison.
Attention focused on the new ZF four speed transmission, the independent suspension and the underslung chassis configuration which facilitated the lower stance of the body.
Although for Röhr and his team some of these features may no longer have seemed so innovative as they had when he had pioneered them ten years earlier, they did set Adler apart from the more cautious/conservative approach to car design that continued to be apparent in the mainstream models produced by Opel and Mercedes-Benz during the first half of the decade.
Commercially the new Favorit failed to take the market by storm and was withdrawn after a year, but the 6-cylinder Standard continued to sell in respectable numbers, with further improvements and a name change along the way, till 1940.
The characteristic Röhr underslung chassis permitted a low centre of gravity and above-average road holding and, while giving the car a far more modern and dynamic look than the new competitor offering from Opel which also appeared in 1934.
[1] The position urgently needed filling and Röhr brought to it his considerable reputation and experience, but he was nevertheless seen as something of an outsider by the company board, under the chairmanship of Wilhelm Kissel [de; it; ja; mg] (who back in 1928/29 had already seen off an earlier brilliant Technical Director, Ferdinand Porsche).
His insistence on bringing his team with him from outside, and his willingness to question articles of faith on matters such as the way a Mercedes-Benz had its rear suspension arranged, again failed to endear him to senior colleagues.
There was no suggestion that Hans Gustav Röhr might be Jewish; but he had nevertheless married a French wife which in Hitler's Germany could readily be questioned as unpatriotic.
Most German automakers had responded to the introduction of all-steel car bodies a few years earlier by entering into a contract with the Berlin-based specialised steel-body maker, Ambi Budd.
The board decision not to progress his designs to production, taken in 1936, was a hard blow for Röhr, reflecting his continuing position as an outsider and, some have argued, a certain personal inflexibility.