Growth: It's the magic investing buzzword. Every investor scours quarterly and annual reports hoping to see huge growth in companies' top and bottom lines, and every investor hopes to hear management talk endlessly about how its future growth potential is lucrative.

Of course, organic growth can be difficult for businesses to accelerate at the drop of a hat. However, acquisitions can be a much faster way to add incremental growth to the top line. That's exactly what AutoNation (NYSE:AN) has been doing this year, and by the time the books are closed on 2015, it will go down as the company's biggest year for acquisitions since 1999.

Buy, buy, buy!
"We continue to seek acquisitions to leverage our scale, expand the AutoNation brand and provide a peerless experience to more customers," AutoNation CEO Mike Jackson said in an August press release.

Already the largest U.S. dealership group, AutoNation recently agreed to purchase 16 stores that generated more than $600 million in annual revenue. Its purchase of Carl Gregory Enterprises was the company's largest single dealership purchase since 2001.

While this is a good move for AutoNation to grow its top line, it's also important for investors to understand what exactly the dealership group is buying and where. Let's dig in.

What and where?
The larger chunk of the recent acquisitions was the deal for Carl Gregory Enterprises, which operated 13 stores in Georgia, Alabama, and Tennessee. The chain of stores will expand its footprint in the Southeast and make Georgia one of its most important markets -- perhaps as large as its fourth-largest market by revenue, behind only Florida, Texas, and California. The remaining purchases were from the Valley Motors Auto Group, which provided three stores in Maryland and the Washington, D.C., area, which increases AutoNation's store count to 253 from coast to coast.

The acquisitions will expand the company's footprint in the Southeast and is a positive move for investors, as the company generated a lopsided 66% of total revenue from stores operating in Florida, Texas, and California last year. That leaves AutoNation exposed to two of America's most significant housing markets, in Florida and California. This presents a risk because in the event of a recession that would hurt automotive sales, the housing market would likely also suffer and further cripple consumer wealth, which would exacerbate the auto sales problem in these markets. Now, with the acquisition of Carl Gregory Enterprises, which adds 11 stores in Georgia -- roughly doubling its dealership count in the state -- AutoNation will have a strong presence outside of its stronghold in Florida, Texas and California.

Investors should also look beyond where the acquisitions are located and better understand what exactly these purchases bring to the table. First, let's look at the makeup of AutoNation's dealerships at the end of 2014, so we can better understand how these acquisitions fit in.

Chart by author. Data source: AutoNation 2014 annual report.

That's a snapshot of how much revenue certain types of dealerships generated for AutoNation last year. Brands under the Fiat Chrysler Automobiles umbrella ranked eighth on that graph, but AutoNation took a step in the right direction and capitalized on very hot-selling FCA brands through its recent acquisition: six Chrysler-Dodge-Jeep-Ram stores were purchased within the 13-store Carl Gregory acquisition. That would boost the number of AutoNation dealerships selling FCA products by roughly 25% from the end of 2014 levels. This is important because the third-largest "Detroit" automaker has steadily increased its share of the U.S. market, and September marked the 66th consecutive month of year-over-year sales gains for FCA -- a very impressive statistic. 

Also included in that acquisition were three Hyundai stores, two Ford-Lincoln stores, and one store each of Honda and Volkswagen. From the Valley Motors' acquisition, AutoNation gained a Mercedes-Benz store, an Audi store, and a Subaru/Volkswagen store.

Those are just the two most recent acquisitions, and AutoNation had already made smaller acquisitions earlier in 2015 that generate roughly $320 million in annual revenue. So far through 2015, AutoNation's acquisitions, if all completed, will generate an estimated $929 million in annual revenue -- which is a huge jump from the company's five purchased stores in 2014, which generated about $450 million in revenue annually.

It's clear that AutoNation is attempting to aggressively grow its revenue through acquisitions, and more important, this year's acquisitions are helping reduce the company's dependence on its Florida-, Texas-, and California-based markets. These acquisitions should fuel growth for AutoNation investors, and if the company can continue to scale its business, it should be a healthy couple of years.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.