Just my observation based on, among other things, seeing scores or hundreds of BMWs at track DE's and a total of zero MB at the track over that span (7 years, 4 different tracks). Plus the fact that BMWs always offer manual transmission on multiple vehicle lines (eg, you can get manual trans. on the 5-series w/ 3 different engines and on the 3-series with 3 different engines) whereas until very recently MB did not offer manual transmission on any model in US, and now it is limited to a couple of models.

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2005 Mercedes C230k sport sedan, 6 speed
1987 Porsche 924S - 968-engined track car