The news comes just a couple of years after the French manufacturer unveiled its New Distribution Project, which it boasted would cut delivery time from eight to two weeks.
But supply, logistical and distribution problems have forced Renault to scrap the plan.
'We have not managed 15-day delivery,' said Francois Hinfray, Renault's senior vice president for sales and marketing, 'but 21% of customers do receive their cars within that time frame.'
'The failure to reach the 15-day goal will be seen as proof that the car industry is failing to find ways to improve its distribution systems,' said automotive industry expert Garel Rhys.
'Most manufacturers say they have succeeded in making the supply chains and production processes significantly more efficient over the past 10 years – but car distribution remains a big problem for the industry.
'In many post-production areas, the car industry remains stuck in the 1970s. It is still working to a system that builds the cars for storage, and then tries to sell the stock cars to buyers.'
But Hinfray says the New Distribution Project acted as a spur to improve distribution from Renault's 11 plants across Europe. 'The effort has worked,' he said. 'Order-to-delivery times is down to an average of four weeks.'
By the end of this year, Renault says it hopes 60% of its cars will be built to order. That compares with just 25% before the New Distribution Project was launched.
The proportion of built-to-order cars varies throughout Europe - with much higher levels in northern Europe compared with southern Europe.
Hinfray said unreliable railways - particularly in strike-prone France - were a major problem for car companies hoping to improve distribution efficiency.