However the Mini had significant transmission problems early in its production run and the arrangement had poor refinement, high noise levels and was awkward to service.

The early issues were resolved and the concept spread to larger BMC products, notably the 1100/1300 series built in Italy by Innocenti.

These larger models did not require the transmission-in-sump arrangement for the purposes of space utilization (as on the Mini) but retained it for design and parts commonality.

Fiat's chief designer, Dante Giacosa, recognized the potential of the concept and sought ways to improve on it - namely by removing the transmission from the sump.

Fiat was cautiously accepting of Giacosa's proposal and decided to experiment without risking damage to the image of its popular Fiat-branded cars.

With the transmission mounted end-on to the engine and the final drive therefore offset from the car's centre line, the Primula had unequal-length driveshafts.