Both need plenty of loving care and regular checks, have a habit of playing up at the worst possible moments, and produce toxic emissions.
The book is a how-to guide to caring for babies
Yes, the similarities between cars and babies are clear.
And now, for macho, mechanically-minded dads, car manual publisher Haynes has produced a how-to guide to caring for their tots.
The book, entitled Baby and containing a host of fault-finding charts for problems ranging from fever to rashes, is written by a doctor rather than a mechanic.
It was the brainchild of Haynes boss - and new dad - J Haynes
It tells dads how to "maintain baby's bodywork in optimum condition, prevent corrosion of vital parts, and decide when to call in professional assistance."
There is advice on what performance to expect from birth up to the age of two, what to do in emergencies, and how to cope with teething, crying and bath-time.
The latest addition to the Haynes Manual family was the brainchild of the firm's managing director - and new dad - J Haynes.
He said: "When my wife was six months pregnant I walked into our bedroom and noticed that on her side of the bed there was a vast array of baby books and books on pregnancy.
"Then I looked at my side of the bed - there wasn't a single book, and I thought it was about time we did a new manual."
It provides fault-finding charts to detect common problems
Author and father-of-four Dr Ian Banks said the book was aimed at telling men about the workings of babies rather than telling them how to be fathers.
"I'm not into this new-age modern man stuff," he said.
"I don't want to make dads experts in baby talk or the various cures for nappy rash.
"I want to give them handy tips that will help them cope, not turn them into virtual mothers.
"The car approach is a bit of fun, but I want men to see beyond the joke - the message is they can play a fuller part in caring for baby without having to hang their masculinity on a hook."
Dr Banks's previous Haynes handbook, Man, became a best-seller last year.
For every copy of the £12.99 Baby manual sold, 50p will be given to the Great Ormond Street Hospital Children's Charity.