Millennials are more prepared than their parents to cover the costs of an unexpected emergency

Let's face it: It's really not a matter of if you'll need to fork over cash for a car or home repair, child expense, or medical emergency, but a matter of when.

"No matter how well you plan or how positively you think, there are always things out of your control that can go wrong," David Bach writes in his bestseller "The Automatic Millionaire," which was re-released in December.

Bach's right. In a new report from Bankrate, 45% of Americans said they or their immediate family faced an unexpected expense in the past year.

And yet, only 41% of Americans are prepared to pay for such an expense with their savings, according to Bankrate. Another 20% said they'd cut back on spending in another area to cope, while the rest say they'll use credit cards or retirement funds, or borrow money.

Millennials outpace the other generations in this regard. Bankrate found they were the most prepared generation, with 45% claiming they'd pay for an unexpected cost with their savings and 24% saying they'd cut back on spending, rather than having to borrow or use a credit card.

That shows a divergence between millennials and their parents, who mostly hail from the baby boom generation. Only 39% of boomers said they'd cover an unexpected cost with savings, while 17% said they'd cut back on spending. A full quarter of boomers said they'd pay the charge with plastic, while only 15% of millennials said they'd rely on credit cards.

But it's worth noting Bankrate found that adults without kids are more likely to use savings for an unexpected expense (43%) than those with children (36%), potentially explaining why millennials - who are waiting longer to have kids than generations before them - are most prepared.

Further, Bankrate found that half of the highest-income households - those earning $75,000 or more a year - and college graduates lack enough savings to cover a $500 car repair or $1,000 emergency room visit.

"People lose their jobs, their health, their spouses. The economy can go sour, the stock market can drop, businesses can go bankrupt. Circumstances change. If there's anything you can count on, it's that life is filled with unexpected changes," writes Bach, who has spent 25 years in the wealth management industry and became a millionaire by age 30 by increasing his automated savings over several years.

Bankrate's report underscores Bach's comments during a previous Facebook Live interview with Business Insider. Although nearly half of Americans don't have enough money on hand to cover an emergency, Bach says, referencing troubling research from the Federal Reserve, millions of those people will buy a coffee at Starbucks today and expect to buy the new $800 iPhone next year.

"So we have money in America, the problem is we're not keeping any of it," Bach said. "'The Automatic Millionaire' mantra is: Pay yourself first and let's put ourselves first."