Interesting! When it comes to Lexus's situation in Germany I think the low demand is due to several factors:
From my experience, many Germans who aren't into cars don't even know the brand exists. Also, unlike BMW, Audi and Mercedes, Lexus and other Japanese brands have traditionally focused more on smooth luxury cruising (i.e. soft suspension, CVT transmission etc.) which won't be as appealing in a country with no speed limit on the highway. I've driven both a Mazda 6 and VW Passat as a company car and they feel completely different. The Mazda started feeling a little nervous and fragile above 120 mph whereas the Passat felt really calm and planted. The difference is even more pronounced in more upscale models like the A6/A7 or the 5 Series and above.
Lexus also seems to be a little behind when it comes to infotainment and we all know how much emphasis luxury car buyers place onto that nowadays. I know that their drivetrains and build quality are among the best but, again, the average person who is not into cars doesn't know that. They just see a design language that's unusual and weird to them and infotainment that looks a little dated. ALso Lexus have traditionally focused more on Hybrids instead of the vastly more popular Diesel. Hybrids were a USP in the early 2000's but nowadays pretty much every brand offers at least one Hybrid model.
The only foreign luxury brand (if you want to categorize it as a luxury brand) I can think of that has been succesful in Germany is Tesla. I live in a major city and you see them everywhere, especially in more affluent areas.
Edit: Btw I also learned that Germany is apparently Ferrari's second largest market after the US. I wouldn't have expected that.
