The Custom Concept has been in the background since it was unveiled in 2008 but because the news has been so non-committal in the past two years, most people had assumed BMW had decided not to pursue the building of the bike.
It now appears that speculation was incorrect and the advanced state of the bike makes it look likely it will appear in finished form later this year.
These spy shots, taken at the same time as those of the naked S1000RR and R1250GS water-cooled variants at a private BMW test track show what looks like a well-advanced prototype bike based around the current 110bhp air-cooled Boxer twin. It gets a bespoke steel trellis frame, a new fuel tank and minimal seat unit.
Whether this quite traditional and classic roadster style of bike is the actual production version of the Custom Concept, or a separate model to add the R1200R range is something only those within BMW know for certain.
And the firm certainly isn’t letting anything out of the bag about it by refusing, as always, to comment on future models.
What we can see from the bike being tested here is a fairly classic and retro styled roadster with conventional upside down forks with what looks like the single headlight unit and clocks from the recently updated R1200R.
BMW has kept the design both simple and easy to develop at the lowest possible cost by raiding the wide range of parts in the BMW range.
The Boxer engine is the current model used in the R1200GS, R1200RT and R1200R models; as is the swingarm. The forks look like those from the R1200R along with the front light and clocks (although these may change before production).