The advantages of testing cars virtually, rather than building a prototype or a mule car, are numerous.

ECONOMIST: Car design

We tried driving the walks, madly piloting our rented car along mule tracks and logging trails.

WSJ: James Lasdun on the Dark Side of Writing Travel Books | Traveler's Tale

But there are also warnings about getting caught up in drug smuggling, either by being used as a "blind mule" who doesn't know drugs have been put in their car or luggage, or by being strong-armed by smugglers who threaten harm if a person doesn't carry drugs.

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