Motor Girls on the Coast or the Waif from the Sea

When Cora Kimball got her new auto for her birthday she had no idea what adventures would start for her and brother Jack. Where did Ed's money and bonds disappear? Were they misplaced or were they stolen and lost forever.
Did the conceited Sid Wilcox have something to do with the missing money, with the help of Ida Giles? And what did the obnoxious Lem Gildy have to do with it all?
Cora and her friends experience mystery and adventure as The Motor Girls.
Margaret Penrose was a house pseudonym used by the Stratemeyer Syndicate.
The name Margaret Penrose was used for:
* The Dorothy Dale series
* The Radio Girls series (Later reprinted as The Campfire Girls series)
* The Motor Girls series
Many of these books were written by Lilian Garis.
The Stratemeyer Syndicate was the producer of a number of mystery series for children, including Nancy Drew, the Hardy Boys, the various Tom Swift series, the Bobbsey Twins, the Rover Boys, and others.