Cunningham and Petrov: The Mystery of the Missing Aeroplane chapter 3

and

The Naughtiest Girl Continued: The Naughtiest Girl Keeps a Secret

A mystified garage mechanic had been called after Enid had made repeated, unsuccessful attempts to start the engine. She remembered four days later, after the car had been thoroughly overhauled and sparking plugs renewed that she had ‘poured paraffin oil into the car battery instead of water’.

A little anecdote from Enid Blyton A Biography by Barbara Stoney. Clearly Enid’s mind was on her next book at the time!