Is a cordless handheld or a corded wet/dry vac better for cars?

It depends on the mess. Across the reviewers we read, cordless handhelds win on convenience for dust, crumbs and light pet hair, while corded wet/dry shop vacs deliver far more suction and can handle spills, mud and deep carpet debris. Detailers in r/AutoDetailing generally favor a wet/dry unit for serious interior cleaning.