It probably comes from an expression used for many years by people who fix parts of cars and trucks.

VOA: special.2009.11.29

But I've heard of some people who have many many cars.

但是我也听说过有些人会买很多辆车。

How many实战 - SpeakingMax英语口语达人

How many cars do you have?

你有几辆车？

How many实战 - SpeakingMax英语口语达人

Many of their movies show scenes in which the actors chase each other in cars, or in airplanes or on foot.

VOA: special.2010.07.25

But for the most part, I mean, I've seen... I don't know how many times I've seen paparazzi almost get hit by cars.

但是大部分情况下，我是说，我见过……我都忘了多少次我看到狗仔队差点被车撞上。

溺爱是一种伤害 - SpeakingMax英语口语达人

Mister Durant had a new idea for a car company that produced many different kinds of cars.

VOA: special.2009.10.09

There are many cable cars in San Francisco. What are they here for?

旧金山有很多有线缆车。它们的用途是什么呢？

旧金山的公共交通 - SpeakingMax英语口语达人

For the first time in many months, large numbers of Americans have been buying new cars.

VOA: special.2009.08.07

Do many people in London have cars?

住在伦敦的人有私家车吗？

公共交通更方便 - SpeakingMax英语口语达人

If you have ever visited, you might have noticed the popular license plates on many D.C.cars.

VOA: special.2009.03.20

Many places struggle with traffic problems as more and more cars fill the roads.

VOA: special.2010.01.11

And,it continued to improve its designs, offering customers many kinds of cars.

VOA: special.2009.10.09

Many of the victims were trapped inside their cars and trucks when the explosion occurred.

VOA: standard.2009.06.01

Many are challenging GM and Chrysler's decision to take their cars off the road.

VOA: standard.2009.06.04

Interpol says thousands of luxury cars stolen in Belgium,France, and Japan enter Cameroon's port of Douala each year, many bound for buyers in neighboring Equatorial Guinea and Gabon.

VOA: standard.2009.11.09

Private cars were also used to ferry the many wounded to hospitals.

VOA: standard.2009.10.25