When Tesla unveiled the Tesla Semi late last year, it managed to pull off the impossible. Sure, the Tesla Semi’s specs are impressive, but even more astounding was Tesla’s ability to get people interested in and excited about a semi-truck in the first place. Indeed, there’s something unique about the Tesla brand that just seems to engender excitement in a way that most other auto manufacturers could only dream of.

Of course, the Tesla Semi itself is no slouch. Spec wise, the entry-level Tesla Semi boasts 300 miles of range and can go from 0-60 MPH in 20 seconds flat while hauling an 80,000 pound trailer. While the specs are impressive, the main appeal of the Tesla Semi rests on its ability to save companies a lot of money. Indeed, during the Tesla Semi unveiling, Elon Musk boasted that the Tesla Semi is not only cheaper than diesel alternatives, but that it’s also more wallet-friendly than rail.

“It’s s not just economic suicide to use one diesel truck,” Musk explained, “it’s economic suicide for rail. This beats rail.”

In turn, it’s no surprise that companies who routinely ship cargo across the country are placing large orders for Tesla Semi vehicles. Pepsi, for example, has already pre-ordered 100 Tesla Semi trucks while UPS has ordered 125 trucks. And speaking to the cost-savings that the Tesla Semi may offer to buyers over the long-run, DHL Supply Chain president Jim Monkmeyer recently told Reuters that the difference between a Tesla Semi and a traditional diesel truck could be made up in less than two years “thanks to savings on maintenance and fuel.”

“We are estimating that we could have pay back within a year-and-a-half based on energy usage as well as lower maintenance cost,” Monkmeyer said. “The maintenance savings can be enormous as well. Just because the engines are much simpler in terms of the number of parts and the complexities of the parts.”

And never one to shy away from bold predictions, Musk late last night took to Twitter and said that the specs accompanying the Tesla Semi might be more impressive once it actually starts shipping.

Am feeling optimistic about beating the Semi specs announced at the unveiling for the same price. The Tesla Semi will be something really special. — Elon Musk (@elonmusk) February 24, 2018

It’s an intriguing tweet, to be sure, but Musk played coy about which specs in particular might see an improvement. While the Tesla Semi’s acceleration is certainly nice, if not downright impressive, an improvement on range might help attract even more buyers. As it stands now, the Tesla Semi is available in two configurations, one with 300 miles of range which costs $150,000 and another with 500 miles of range which costs $180,000.

Barring any delays, the Tesla Semi will begin shipping sometime in 2019.