The suspect was detained in Wolverhampton on Tuesday after the woman was found in a layby off the main road between Wolverhampton and Bridgnorth in the early hours of Monday.
Meanwhile Staffordshire Police have said they are now "close" to establishing who the murder victim was.
She had significant burn marks to her body and is thought to have been driven to the main road before being set on fire.
Although her identity, age and ethnicity are yet to be confirmed due to the severity of the burns, detectives believe the woman was aged between her late teens and 30 years old.
WATCH: Detectives appeal for help identifying victim
Staffordshire Police has confirmed that a post-mortem has taken place and the cause of the woman's death is under further investigation.
Meanwhile the A454 remains shut on the western edge of Wolverhampton three days after the woman was found.
A 41-year-old man from Wolverhampton has been arrested on suspicion of murder and remained in custody on Wednesday afternoon.
Detective Superintendent Tom Chisholm, who is leading the investigation, said: “We are at the early stages of a major investigation and we have had a great response from the public so far, but we are keen to get more information.
Map shows where woman was found:
"We have made an early arrest but I must stress this is not the end of our investigation and we still need the public’s help.
“We believe she was driven to the site. Did you witness anything suspicious or see any vehicles in the area between 1am and 3am on Monday morning?
"Do have local dash-cam or CCTV footage?”
The woman was found by police just before 3am on Monday after reports of suspicious activity on the A454 Bridgnorth Road, just south of Perton on the edge of Wolverhampton.
The area has been cordoned off by police since, with forensic tents put up at the scene as officers scour the nearby area.
Bridgnorth Road was shut off from Tinacre Hill to Jenny Walkers Lane as a result.
The murder suspect is understood to have been detained in the Finchfield area of the city.
Anyone who believes they may know who the woman is, or was in the area of the Bridgnorth Road between 1am and 3am on Monday, is asked to contact police.
Anyone with information is asked to call Staffordshire Police on 101 visit mipp.police.uk/operation/staffs21h10-po1, quoting incident number 42 of August 9, or contact Crimestoppers anonymously on 0800 555111.