The Berkshire rail crash has been described as a "tragic accident" by the government after a report found no fault with rail equipment or staff.
All eight carriages left the tracks in the accident
Transport Secretary Alistair Darling said "we owe it to those who were involved" to find out what happened.
Interim findings from the Health and Safety Executive said the train driver had just a few seconds to brake before it hit a car on a level crossing.
Seven people were killed in the crash, near Ufton Nervet, on Saturday evening.
The report said early signs suggested car driver Brian Drysdale made "no attempt" to move his car from the level crossing as the train approached.
An inquest into the deaths of all the victims was opened and adjourned at Reading Coroner's Court on Wednesday.
The coroner heard brief accounts of the causes of each of the victims' deaths.
Det Supt Eamonn Carroll, leading the investigation for the British Transport Police, then told the court how Mr Drysdale was fully clothed with his seat belt on at the time of the accident.
Following the high-speed crash, "he came out of the car, and the force that was involved, with his seatbelt on, has caused disruption to clothing," said Mr Carroll.
The inquest also heard that Mr Drysdale was not drunk and had not taken drugs at the time of the crash.
The eight-carriage train ploughed into his car at high speed at 1812 GMT, resulting in his death, train driver Stanley Martin's and five of the train's passengers.
The HSE report said 37 of the approximately 180 passengers and four staff on board were taken to hospital.
Mr Martin was travelling at the permitted speed and the level crossing was in full working order, the report stated.
Although the front train wheels derailed immediately the train stayed upright. But when the train passed over a set of points further down the line every carriage came off the tracks.
The front of the First Great Western train ploughed into the embankment, while the rear power car on the train continued to propel the train forward, investigators found.
Announcing the report to the House of Commons, Mr Darling said: "I would like especially to praise the work of the Thames Valley emergency services."
RAIL CRASH VICTIMS
Train driver Stanley Martin, 54, from Torquay
Anjanette Rossi, 38, of Speen, Berkshire
Ms Rossi's daughter Louella Main, 9
Emily Webster, 14, from Moretonhampstead, Devon
Barry Strevens, 55, from Wells, Somerset
Leslie Charles Matthews (Charlie), 72, from Warminster
Brian Drysdale, 39, from Reading
If there are wider safety lessons to be learned, then the rail industry and government will pursue them, he said.
Train drivers' union Aslef welcomed the speedy publication of the report, saying it strengthened the union's calls for more safety measures at level crossings.
The father of victim Emily Webster, 14, has called for seat belts in high speed trains.
Work to clear the wreckage from the accident site began on Monday night and is expected to last two or three days.
Police are still looking into why Mr Drysdale's car was stopped on the crossing, and have not ruled out suicide.
The HSE inquiry and police investigations are continuing.
Thames Valley Police wants all passengers who were on the train but did not attend hospital to contact them on 0870 0100732 between 0800 GMT and midnight so they can be checked off against the list of passengers.