Investors piled into Ford Motor Co.'s first automotive borrowing in almost four years, allowing the company to slash interest rates on a $2.8 billion debt sale as it boosts spending on self-driving cars, mobility services and electrified vehicles.

The automaker sold 10-year and 30-year notes Monday, according to data compiled by Bloomberg. Investors put in about $8.7 billion of orders for the bonds, said a person familiar with the matter, letting Ford sell more than the $2 billion it initially anticipated. Ford's last automotive issue was for $2 billion in January 2013. The company said its auto business had $13.1 billion in debt at the end of September and net cash of $11.2 billion.

Ford has undertaken an expensive effort to transform itself into a mobility company that can take on upstarts such as Uber Technologies Inc. and Google. The cost of that conversion is causing profits to fall this year and next. The second-largest U.S. carmaker has promised to put 100,000 robot taxis — without steering wheel, gas or brake pedals — on the road in five years. It's also investing $4.5 billion to convert 40 percent of its lineup to electrified vehicles by 2020 and is offering bike sharing and a commuter van service in San Francisco.