As a car driver without a cabin air filter, (are cabin air filters even effective against exhaust gases?) both diesel trucks and motorcycles require me to close my windows and vents because of the smell.

At least cars have smog equipment to reduce the emissions. Motorcycles mostly don't.

Most motorcycles made from 2017 onward have factory emissions equipment with cleanliness similar to cars (due to the Euro5 regulations from that year forward). Since most bikes have one configuration globally, even US models implemented Euro5.

You could wear an FFP2 or FFP3 mask with a valve.