I bought a MINI Countryman F60 and skimped on the 'Storage Pack'. If you did too and regret it because of the boot floor situation and the dealership is reluctant to help, I've done the research and came up with a solution that while not ideal, will work for those situations when you absolutely MUST have a flat boot floor and don't want to spend too much (parts + labour) on getting the genuine part installed.
With a bit of DIY you can get a flat floor for about a third of the price of parts alone.
I've designed and built the flat boot floor shelf from common materials. MDF, some aluminium edging and automotive carpet and glue. The most important part of this information is the PDF/SVG/DXF file linked below that allows a precise, CNC cut of the MDF. The rest is mostly redundant rambling.
It is a less-safe alternative to spending approximately £250 on genuine BMW part '51 47 7 380 665' and supporting parts, especially since they are NoS (No Stock) parts that need to be specially ordered from factory.
It is not an exact replica of '51 47 7 380 665' -- the original is 2kg lighter and slightly stiffer as its made out of epoxy resin/fibreglass composite. Having said that, the 18mm MDF provides reasonable stiffness and moisture resistance once sealed properly.
The two elements of this DIY hack hinge only using the carpet. Consider installing three piano hinges for more stiffness and loading capacity. If you add them, subtract appropriately from the length of the base element.
The original part is anchored to the car for crash resilience. You *must* understand that neither this DIY part nor the original part pass crash test regulations without the supporting mounts. Do not be tempted to just plop the '51 47 7 380 665' in your car alone and call it a day. The smart BMW engineers have put a lot of thought into this. Do not ignore it!
This project part has not been crash-tested. You must assume and expect it to fail in any and all crash scenarios in the most spectacular and catastrophic way imaginable. I am not an engineer. This is not engineering advice.
It would be sensible to only use it when you are transporting large items requiring a flat floor -- in which case the safety in a crash is already compromised by a large, unsecured mass inside the cabin, where the squishy bits are.
For completeness, to do a fully compliant installation, you would need:
Floor carpet, luggage compartment (1) 51 47 7 380 665 €181.50
Trim panel, cross member, trunk (1) 51 47 7 380 671 €48.00
Expanding rivet (4) 07 14 7 401 727 €1.03
Mount for trunk floor panel (1) 51 47 7 380 666 €60.91
Countersunk screw M6X16 (4) 07 11 9 907 139 €1.47
For total of €291.91 or ~£250 ex VAT. Your friendly local dealership will probably charge twice that amount for fitting (merely an opinion; also this list may not be exhaustive, I am not a certified BMW/MINI parts specialist) and add VAT to the prices; so below is the cheapskate alternative.
Those were created in Valentina, a multi-platform tailoring CAD program.
Valentina project page on GitLab
Valentina Downloads for various operating systems
Local copy of Valentina downloads (updated daily)
Two pieces of 18mm 610mm x 1220mm MDF, £17
Two pieces of 1m 11.5mm x 19.5mm aluminium bar, £9
1400mm x 1000mm automotive carpet, £6
500ml can of automotive trim adhesive, £7
250ml can of Rustins Quick Drying MDF Clear Sealer £3.50
6x5/8" twin-thread wood screws, box of 200 - £1.66
Optionally, 3-4 piano hinges (also called butt hinges) of decent quality and some hinge grease. WD40 will also do.
You will also need two small pieces of 9mm MDF 9.5cm x 2.5cm - ask at a local DIY shop for a small offcut.
Links above are not affiliate links. I'm not earning any commission if you decide to buy these items.
From the curved edge, you will need to stretch the fabric as you cover the bottom side as much as it will stretch to go around the curved part. The fabric needs quite a lot of stretch for a good finish but is made to do it. Start at the handle area and work towards the sides in 2-3 sections stretching the fabric towards you as much as you can. It looks impossible at first but it works.
Total cost of materials and services ~£100.
Investigate and experiment with other materials than MDF. Composites. Carbon Fibre. If you have access to such interesting stuff, use it. All you need is the template file for exact dimensions and shapes. I'd hazard a guess that a 3 layer sandwich of fibreglass, resin and some cheap carbon fibre fabric would run rounds around the MDF in terms of stiffness and lightness.
Example 1m x 1m carbon fibre sheet
Example 3m x 1m fibreglass sheet
The world is your oyster!
Prices correct at the time of writing. I am not affiliated with the above-linked entities. I do not endorse the above companies, vendors, or products. I have not received any special pricing or discounts in exchange for mentioning them here. I will not receive any compensation if you decide to follow the above links to purchase the items. Those links are provided for reference and your convenience. I do not guarantee accuracy or fitness for a particular purpose of the linked materials or services. Your experience may vary. This information is provided as-is and without warranty of any kind. Follow at own risk. This is not engineering advice.
MDF is pretty nasty when inhaled in powder form. Wear face and eye protection when working with it especially when cutting/sanding.