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Protoype TUM

This ingenious little vehicle is a successful variation on a well-known theme: it was designed and built from scratch in I978,from CitroŽn mechanical parts and components, by Messrs Marc Lemaire and Charles Agaise, assistant lecturers of the “Engines and Mechanisms” laboratory of the “Technology and Productions Techniques” department of the Nantes “Ecole Nationale Supťrieure de Mťcanique” with the aid of Mr Mace, technician, of Messrs Crac and Lucas, technical teachers, and of the 2nd- and 3rd-year engineering students.


Its creators have named it TUM or "Transport urbain minimal” (Minimum Urban Transport), a title which summarizes their objectives.

Minimum without a shadow of doubt: the TUM’s overall length is only 7’ I0”‚ or over 3 feet less than the LNA which is already very compact. The width, 5’ 3”, is that of a normal car. It is also 5’ 3” tall.  Weight: nearly 1,322 lbs.

In order to compensate its very short wheelbase (4’ 5"), the front and rear tracks are rather wide (4’ 8 ľ”) to ensure proper balance for the vehicle.

The four 12" wheels are independent, mounted on a 2 CV axle arm connected to a variable-flexibility mechanical suspension whose mechanism is on each side concentrated in the centre of the vehicle, and easily accessible through lateral trapdoors.


The TUM is a front-wheel drive car. Its engine is the 435-cc flat twin of the Dyane. Also from the Dyane are the gearbox (4 forward speeds + reverse), with its lever on a central bracket, and the centrifugal clutch.

The CitroŽn steering is of the rack-and-pinion type, with bevel gears. Reduction ratio: 1:14. The turning radius is extremely short: 11’ 5 ĺ” between kerbs.

Fitted on a 20 >< 40 mm (.787” X 1.575”) tubular structure reinforced with welded sheet-steel panels, the body is that of a saloon-estate with overhanging cab. It forms a geometrically shaped steel volume, housing two front seats and a generous loading space at the back.


Three doors: two on the sides, of the "butterfly" type (opening upwards) and a tailgate leaving the rear perfectly clear, folding into 2 horizontally articulated parts, then opening upwards.

Integral front, rear and side bumper of pressed steel and rubber.

Very wide panoramic windscreen with a single 2-speed wiper. Two large windows on each side, those of the doors sliding. The seats pivot, and are adjustable both in inclination and distance from the wheel.

The wheel itself is adjustable for height. The control module and its fascia, beneath the wheel, are those of the CX.

The maximum speed is 59 mph. Petrol consumption varies between 70 and 47 miles per gallon of 2-star petrol, according to use.

What’s the verdict? Not bad. eh?

© 1979 le Double Chevron 55 / 2013 CitroŽnŽt  Thanks to JL