A number of early M3Ws are still used in vintage racing here in UK. These two with V twin engines are from 1929/30, but later models with Ford sidevalve engines are also used. The 3 wheeler club could probably tell you about surviving numbers.
http://www.mtwc.co.uk/

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Mallory Park race meeting 24 Sept 2016
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This car, driven by Sue Darbyshire, hit some oil on track and spun off. Sue went to hospital but was discharged the same evening. Although damaged, I'm sure the car will be back racing before too long.
Gerry