Test drive report of the 15-Six H with power steering (3-5 April 1954)

In this document

Test route and timeline

The handwritten report records a road test on vehicle ELV 412, a "6H with Power Steering and Hydr. Brake" p. 1, conducted from Saturday to Monday.

• Saturday: departure from Chaville at 4:15 AM, with stops for lack of water/fuel at Mâcon and Orgon, arrival in Lyon (9:35-9:50 AM) then Avignon (12:25 PM) and Saint-Tropez at 2:55 PM, i.e., 921 km covered "in 10H40-23'" at an average speed of approximately 90 km/h p. 1.
• Sunday: after tightening the cylinder head and filling up with water, departure from Saint-Tropez at 3:50 PM for a mountain route (La Garde Freinet, Draguignan, Comps, Castellane, Digne, Sisteron, Gap, Col Bayard, Corps, Laffrey), at approximately 60 km/h average on winding roads, then 68 km/h on a night journey "limited by side lighting", arrival in Laffrey at 9:20 PM after 344 km p. 1. The notes mention "Seat study" twice.
• Monday: departure from Laffrey at 9:35 AM, passing through Grenoble, Bourg, Tournus, Auxerre, Moret (regular water refills, including one at Chenove), return to Chaville at 5:55 PM after 660 km in 7H45, at approximately 85 km/h p. 1.

Observations on power steering

The second page details driving impressions: "Lack of fixed point in a straight line", hands resting on thighs, elbows against the backrest, the wrist working alone "most of the time" — hence the desire for "two armrests" p. 2.

On a winding mountain road, the author notes that the seat must be "bucket-style" because one cannot lean on the steering wheel, the effort on the steering wheel being identical for all drivers but the centrifugal force experienced being proportional to each person's weight. The document attributes to a certain Mr Hermet a long-standing insistence on "enveloping seats" p. 2, concluding that a "Seat study" is "indispensable" p. 2.

Other technical observations

• Servo-brake: "Too much brake at the rear when empty" with approximately 50 kg of luggage p. 2.
• Suspension: the circuit is considered "ideal for tasting the suspension in all cases", with mention of "1st model deformable disc shock absorbers" p. 2.
• Engine: oil consumption of approximately 1 litre per 1000 km, water consumption "without overheating", the reassembly of the cylinder head having changed nothing p. 2.
• Hydraulics in general: "Nothing to report" p. 2.

Context

This test is situated in the development phase of the Traction Avant 15-Six H, the last evolution of the model before the arrival of the DS in 1955. The equipment tested — power steering, hydraulic brakes, disc shock absorber suspension — foreshadows the research that would lead to the hydropneumatic suspension (whose plans by Paul Magès date back to 17 February 1944, Hydropneumatic suspension plans with differential interaction) and the generalized hydraulic assistance of the DS, presented on 6 October 1955. The Chaville–Saint-Tropez–Grenoble–Chaville route corresponds to roads known to be demanding (alpine passes, Var bends), typical of Citroën test routes of the time to test road holding and long-distance comfort.

Archivist's perspective

This document clearly illustrates the working method of Paul Magès: multi-day road tests, in varied real-world conditions (mountain, night, long distance), with precise records of times and mileages p. 1, followed by fine qualitative observations on driving feel p. 2. This test, dated 3 to 5 April 1954, is in continuity with the hydropneumatic suspension tests conducted on the 2 CV from May-July 1946 (Notebook of the first tests of the 2 CV with hydropneumatic suspension), a year and a half before the presentation of the DS.

The reflection on the link between centrifugal force, driver weight and the need for an enveloping seat is particularly interesting: it shows that the ergonomics of the driving position were thought of in synergy with the hydraulic devices, not as a separate subject. The mention of "Mr Hermet" suggests collective work within the test teams, but his exact role is not specified in this document.

This piece thus documents a validation stage directly upstream of the developments that would lead to the DS presented eighteen months later, on 6 October 1955.