Fiat Chrysler's Jeep Brand is sending sales to new heights. Source: Fiat Chrysler Automobiles

Fiat Chrysler Automobiles (NASDAQOTH:FIATY) recently outlined its strategy to assert itself as a new global powerhouse automaker. It's an ambitious plan, to say the least, and a plan that was received with a lot of skepticism among automotive analysts -- myself included. But despite the questions revolving around FCA's plan for the next five years, what you can't take away from the automaker is the progress it has made over the previous five years.

What have you done for me lately?
Let's start with the most recent, and perhaps most flawed, data. FCA has performed extremely well this year in terms of year-over-year sales gains.

Graph by author. Source: individual company monthly sales releases

FCA's sales are up 12% through April, compared to last year. That compares pretty favorably to its competitors in Detroit, Ford Motor Company (NYSE:F) and General Motors (NYSE:GM), which posted a 2.1% decline and 0.1% gain, respectively, over the same time frame.

While FCA's sales gains through April are impressive, it led me to more questions than answers. When you consider that FCA had easier year-over-year sales comparisons to work from, as well as starting from a lower sales volume -- making larger gains easier to accomplish -- how much progress is FCA really making?

The answer surprised me: quite a bit of progress.

Graph by author. Source: Individual company annual sales releases

As you can see in the graph above, FCA's trend line has closed the gap on General Motors and Ford, even as sales for all three automakers rose higher.

The narrowed gap is also apparent in U.S. market share through April, compared to last year, with FCA gaining 100 basis points from 11.7% to 12.7%. Over the same time frame Ford's U.S. market share dropped from 16.2% to 15.4% and General Motors declined from 18.1% to 17.6%. The story was very similar when looking at other major automakers in the U.S. where Toyota's and Honda's market share dropped 20 and 50 basis points to 14% and 8.9%, respectively.

Let's try looking at the information from a different angle; one that more directly compares FCA to rivals Ford and General Motors.

Graph by author. Source: Individual company monthly sales releases

The graph above essentially shows the progress of FCA in reaching the same sales volume as Ford and General Motors. Five years ago FCA didn't even sell half the volume of vehicles General Motors did in the U.S. market; now it's selling nearly 75% of the volume GM is. FCA didn't even sell 60% of the volume that Ford did five years ago and now it has reached more than 80% of Ford's sales volume.

While it's difficult for me to imagine FCA increasing its sales enough here in the U.S. to match its Detroit rivals, the trend speaks for itself: FCA is consistently gaining ground -- and quickly.

Final thoughts
If FCA can reach its five year goal of growing Jeep's brand sales from 732,000 last year to 1.9 million in 2018, and continue selling its Ram truck at a fast clip, it should set the stage for surging profits in the years ahead. If it can revive its Alfa Romeo brand and expand sales with its ultra luxury Maserati brand, it'll be icing on the cake.

I own Ford and General Motors for different reasons, and I'm more bullish on FCA than I have ever been. Though, to be fair, FCA growing its sales and revenues doesn't automatically make it a great investment. FCA still has work to do to improve operations and margins to bring more of its increasing revenues to the bottom line. Ultimately, seeing the progress FCA has made with its sales over the previous five years has earned itself a more in depth look as an investment. Stay tuned.

Daniel Miller owns shares of Ford and General Motors. The Motley Fool recommends Ford and General Motors. The Motley Fool owns shares of Ford. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.