Rules for a $7,500 tax break for electric vehicle purchases and leases recently changed, but more far-reaching changes are expected when President-elect Donald J. Trump takes office.

The two episodes have superficial similarities, including that both suspects used the same car rental app.

Turo, which investigators say was used to acquire the vehicles involved in the attack in New Orleans and explosion in Las Vegas, was emerging as an alternative car-rental service.

Fewer people will be able to afford electric cars and trucks if President-elect Donald J. Trump and Republicans in Congress eliminate a $7,500 federal tax credit.

© Philip Cheung for The New York Times