Patients have objected to “exorbitant” costs after it emerged one in three hospitals in England increased their parking prices last year.
Hospitals made £254 million from parking charges in 2018/19, a record high and a 10% annual increase.
An investigation by the Press Association surveyed 7,883 patients and visitors who used a hospital car park in the past two years and gathered financial data from 144 NHS trusts.
It found that 47 NHS trusts increased their charges between 2017/18 and 2018/19, typically by 10%.
In October, it emerged an NHS worker was issued with two parking fines while undergoing emergency surgery at the hospital where she works.
Earlier this year, there were calls for the NHS to refund staff for the cost of parking at hospitals.
The survey revealed that patients and visitors often struggle to find spaces, experience a lack of disabled parking, long queues and parking meters that do not work.
Overall, 86% of those polled said parking added to the stress of a hospital visit.
One patient said: "The car parks are so busy that from 16.30 until 17.30 it can take nearly one hour to leave the hospital", while another said: "I spent over £102 to visit my wife."
Others described the charges as "a rip-off", "too expensive", "extortionate", "astronomical" and "exorbitant".
As part of their election manifesto pledges, Labour has vowed to scrap all hospital parking charges, while the Conservatives say parking will be free for those in greatest need, including the disabled, parents of sick children staying overnight, staff working night shifts and those regularly needing outpatients.
Almost one in five people who received a parking fine said it was because their appointment overran or for some other reason beyond their control.
A total of 126 NHS trusts provided data to the Press Association following a Freedom of Information (FOI) request.
Data for an extra 18 trusts was collected from figures submitted to NHS Digital as part of their annual estates and returns information collection.
Manchester University NHS Foundation Trust took the most parking revenue in 2018/19 at £6,352,676, up on the £6,285,340 the previous year.
This was followed by University Hospitals Birmingham NHS Foundation Trust (£5,876,000) and University Hospitals Of Leicester NHS Trust (£5,025,860).
Overall, trusts took £254,373,068 in 2018/19, including at least £142,958,247 from patients and visitors and £65,219,879 from staff.
This is up 10% on the £232,236,216 the year before, which included at least £124,864,444 from patients and visitors and £60,060,676 from staff.
Income from parking fines also increased by 8% in 2018/19 to £1,557,749, despite fewer trusts disclosing their income than the previous year.
Just under half (65 out of 124) trusts said their car parks were managed by a private company, with at least 23 of these private firms taking all the fines income. Half of trusts charged for disabled parking.
Only England's hospitals routinely charge for parking - car parks are largely free in Scotland, Wales and Northern Ireland.
A spokeswoman for the Patients Association said: "Charges for car parking at hospitals are a charge on people who are unwell, levied on them because they are unwell. We believe that patients should not be effectively charged for being ill.”
Deputy chief executive of NHS Providers Saffron Cordery said increases in the cost of parking were frustrating, but added: "Car parks are expensive to run for the trusts that own them.
"All charges by trusts for parking cover the day-to-day running of car parking at the hospital, with any surplus reinvested back into wider services for patients or improving these facilities."