Growth stocks are sports cars, and it's understandable in both cases to crack open the hood before buying in to see what kind of power you're getting. Speed matters. However, there's also something to be said about reliability. It's not always the fastest or flashiest vehicle that will get you to your desired destination. 

GoDaddy (GDDY 0.34%) and Sirius XM Holdings (SIRI 1.24%) aren't popular investments among growth stock investors, but they've been cranking out years of positive growth at a steady and predictable pace. They are slow-moving sports cars that don't break down. Let's see why these two stocks have earned their racing stripes in the slow lane. 

Stocks of coins growing higher on soil next to a growing plant.

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GoDaddy

Domain name registrations may not seem like a hotbed industry. The emergence of social media platforms makes it less important to have a dot-com presence, and the industry itself is a cutthroat business. However, GoDaddy has set itself apart as a top brand in this market, and the growth -- slow growth, sure, but growth nonetheless -- will impress you.

GoDaddy has rattled off eight consecutive years of double-digit revenue growth. The streak should stretch to nine in 2021, as GoDaddy's guidance calls for a 13% top-line increase this year.  

The gains aren't going to blow high-octane growth investors away. The annual revenue gains are typically in the teens, and sometimes even lower, as GoDaddy clocked in with 12% and 11% upticks in the last two years, respectively. The high-water mark came in 2013, with a 24% revenue pop. However, GoDaddy's steady growth makes sense. Once you register a domain you're going to want to keep it going year after year, even if it's just a placeholder for an eventual website, platform, or blog. Registrations carry reasonable cover charges for dreams and business ideas waiting to happen.

GoDaddy is the brand everyone knows in this niche, and this has helped it reach out to its more than 20 million customers to offer more services. Less than half of its business is domain name registrations these days, as GoDaddy also offers hosting and presence services as well as business applications. With growing profitability and free cash flows, GoDaddy doesn't deserve to be trading closer to its 52-week lows than its highs with the general market roaring.

Sirius XM Holdings

Satellite radio is another industry that may not seem like a hotbed for slow yet steady growth. Are we really still paying for premium radio, with so many connected cars having access to unlimited free or nearly free aural alternatives? Well, with a record 31.4 million self-pay subscribers at the end of June, we have our answer.

Sirius XM has a steady run of positive annual growth at an even lower level than GoDaddy. Organic revenue has never grown by more than 13% in any year over the past decade. The only year with a higher reported top-line increase was 2019, when results were padded by the acquisition of Pandora Music. 

Premium radio has been a money machine since the merger of Sirius and XM a dozen years ago. Sirius XM is using its free cash flow to provide growing quarterly dividends and buy back its shares. Its share count has been reduced by 40% since 2012, and it's still hungry for more of its own cooking.

The 15% top-line growth it posted in its latest quarter is its headiest organic gain in more than a decade. Sure, that follows depressed quarterly results a year earlier, but it's an encouraging sign that satellite radio is not transitory technology that's going away now that we're driving more again. Sirius XM is growing its subscriber base -- expecting to add another 1.1 million accounts this year -- and this one-time penny stock has evolved into one of the more reliable media stocks