Operation Terror by Murray Leinster

It was a ticklish job getting the car out of the garage and into the street. Lockley was afraid that starting the motor would make a noise which in the silence of the town's absolute abandonment could be heard for a long way. The grinding of the starter, though, lasted only for seconds. It might make men listen, but they could hardly locate it before the motor caught and ran quietly. Also, the trailer-truck was still in motion and making its own noise. Of course it was probably posting watchers and listeners here and there to try to find Lockley and Jill.

So Lockley backed the car into the street as silently as was possible. He did not turn on the lights. He stopped, headed away from the area in which the truck rumbled. He sent the car forward at a crawl. Then an idea occurred to him and cold chills ran down his spine. It is possible to use a short wave receiver to pick up the ignition sparks of a car. Normally such sparkings are grounded so the car's own radio will work. But sometimes a radio is out of order. It was characteristic of Lockley's acquired distrust of luck and chance that he thought of so unlikely a disaster.