It's safe to say that if your state requires helmets for motorcycles, then you need a helmet while driving a M3W.

Texas has not helmet law, so in Texas you don't need a helmet while driving the M3W.

I plan on wearing one for highway driving FWIW, regardless of the law.

1965 Plus 4
2008 997 Turbo Cab
1981 Alfa Spider
1954 Austin Healey 100 (SOLD)
2013 M3W (SOLD)