Uber lost $5.24 billion in the second quarter this year and seems to have no clear path to profitability. But even that loss is understated, because a substantial part of the expense is not included in Uber’s income statement and is instead pushed onto drivers: the wear and tear the job puts on their cars.

Most Uber drivers seem unaware of how their job costs them when it comes to the value of their cars. We spoke with more than 50 Uber drivers in Los Angeles, Portland, Austin, Dallas, Houston and Charleston, S.C., in recent weeks and asked them to tell us their revenues and costs. The revenue—the payments Uber made to them—are recorded in detail, but the costs aren’t as clear. The drivers all included gasoline. Some noted the price of water or candy for riders, and a few included maintenance—but only one detailed the loss in value of the car he was driving, and even then only after we inquired about it specifically.

That driver has an accounting background and wanted to make a little extra money over the holidays. He drove a few-years-old Mercedes M Class SUV, which was worth about $20,000 when he began driving for Uber. He kept meticulous records of his total costs, which he netted out against income. He drove for Uber for a couple of months.

When he stopped driving, he had made about $5,000, but the value of his SUV had dropped from $20,000 to about $15,000. Reviewing his records, the driver found that at least 80% of the miles he drove during that period were for Uber, making about $4,000 of the decline in value attributable to his work for the firm. He was going to have to pay for two service visits, higher insurance rates, and new tires sooner than if he hadn’t been an Uber driver—which all added up to somewhere north of $3,000 in additional costs. In short, he was worse off financially than when he started.

For drivers who depend on Uber to make a living, their cars’ loss in value is serious. If a driver carries passengers for 40,000 miles a year and incurs depreciation of 29 cents a mile—the average reported by the American Automobile Association in 2018—the annual expense is $11,600, or $967 a month, $223 a week, $5.58 an hour based on 40 hours a week.