I believe it was either the A4 or some vw, Audi actually sell a small spring (nothing like the size in the video clips and it clips onto the hinge iirc they was also a plastic cover piece as well, but It might have also involved changing the hinge if it didn;t have the nipples in where the spring goes to.... I still have the info somewhere.
But Rover Idea looks good... but I think I need a pair of new gas struts first anyways.
And I was thinking about a motor like the D3 but seems a lot of work
Daz