The Architecture Behind a 6,000% Throughput Improvement at Hertz

Hertz was a nearly $10 billion company running on technology that its own CEO would publicly call "30 to 40 years old." Underneath it: 1,800 IT systems, six database vendors, 30 rental processing systems, and a core built on IBM AS/400 mainframes running COBOL. Adding a single new product required 18 separate system changes. Meanwhile, Uber and Lyft had captured over 70% of corporate ground transportation spending on expense reports — up from near zero just a few years earlier. The legacy platform wasn't just slow. It was an existential liability. Hertz had already spent $32 million with Accenture on the digital transformation. The result was a website that never went live and code so riddled with defects that every line of frontend work had to be scrapped. Accenture's code couldn't even extend to the other brands — it was built specifically for Hertz when the whole point was a unified platform across Hertz, Dollar, Thrifty, and Firefly. When Accenture was fired, IBM came in through th