I purchased the light grey and found it was still too light after several applications and in my estimation wasn't going to get much darker. I then ordered the dark grey. When I received it, it looked a bit too dark, so I mixed a small amount of the dark and light 50/50, which looked about right. I got pretty close after three applications of the mixture. After it had dried I finished it off with their Leather Protection Cream I'd also ordered, giving it a satin sheen. Looking at it now, I should have gone a step darker, but I was impatient. I don't think I can darken it any more after the protectant, but if I'm unhappy in the future I'll clean the areas with alcohol and darken them some more.

As I mentioned in another post here, I contacted Furniture Clinic for advice after my first attempt with the light grey stuff, sending the same picture I posted here and got a detailed reply recommending their Leather Colorant Kit and other products, which was far too involved and expensive to my liking.
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1992 745, >500k km (now gone, but not forgotten)