Hitting the Gas Pedal on Mileage Awards

Car rental companies, which earlier this year tightened up on frequent-flier awards, are suddenly generous this fall and winter, the traditional slow season. So renters can rack up miles if they act soon.

Avis began the “miles war” by offering triple miles for rentals through Dec. 15. Hertz matched the offer “as a competitive response” last month, said spokeswoman Lauren Garvey. So, for instance, a leisure traveler who spends $300 on a Hertz rental gets credit for 1,800 miles instead of 600 miles on most partner airlines. Some other car firms offer double miles. There are various restrictions on each deal, so it pays to shop around.