Questions were raised about the safety of a Peugeot car today following the death of a middle-aged woman in a head-on smash.
Judith Evans, 56, died in the collision with a Vauxhall Vectra on her way home from work on January 20 last year.
The driver of the Vectra only suffered fractures to her kneecap and internal bruising.
But Mrs Evans, a Chiltern Railways customer relations officer who drove a Peugeot 107, received injuries deemed by experts to be "not typical of the outcomes usually seen in such collisions".
They found that she died in accident circumstances in which an "efficient restraint system" - including a properly functioning seatbelt and airbag - is designed to provide good protection, an inquest into her death heard.
Vehicle Safety Consultancy Ltd (VSC) were asked by Thames Valley Police to consider the protection offered to Mrs Evans in the collision on Coldharbour Way in Aylesbury, Buckinghamshire, after they noticed her injuries seemed unusually severe for the force of the impact.
Peter Gloyns, a mechanical engineer at VSC, told the inquest at High Wycombe Magistrates' Court in Bucks that the car's restraint system did not appear to have worked in the way it would be expected to.
He said: "The accident raises a serious question over the stability of the response of the total restraint system for an occupant of this build and weight in an accident of this severity in which it would be hoped that good protection could be offered."
Mrs Evans, from Aylesbury, Bucks, was of larger than average build, weighing 15 stone and measuring 5ft 9ins, the inquest heard.
Dr Gloyns suggested improvements may be needed to ensure that larger drivers were provided the same protection as slimmer ones.
Reading from VSC's report on the accident, he said: "It is recommended that the outcome of this accident be made known to the vehicle, seat belt and airbag manufacturers involved, so that their designers can consider what measures are needed to improve the total restraint system tolerance to different sized occupants."
Both women were driving at about 30mph when the accident occurred, according to the Vauxhall driver.
But when their vehicles smashed into each other, Mrs Evans did not receive the usual protection provided by the design of the seat, the seat belt and the airbag, the inquest heard.
She suffered multiple fractures, chest injuries and abdominal injuries.
A Peugeot representative told the inquest that the company's seatbelts conformed with the regulations and suggested Mrs Evans was not sitting in the normal position in her seat but was leaning forward.
Barrister William Vandyck, representing Peugeot, said: "Peugeot feel it's more likely the seatbelt was not over the pelvis to start with but over the abdomen."
Mrs Evans' position in the seat may have meant that the "anti-submarining device" built into it to absorb some of the energy in a crash was not restraining her, he added.
The device itself, however, was in line with regulations and was given a four star rating when it was tested.
He also pointed out that the Vauxhall was heavier than the Peugeot and suggested that a hard part of the Vauxhall hit a soft part of the Peugeot, causing greater crushing of the Peugeot.
Mother-of-three Mrs Evans, usually a cautious driver, had been driving in a manner entirely out of keeping with her usual road behaviour, the inquest heard.
The Vauxhall driver, giving evidence at the opening yesterday, broke down in tears as she recalled the crash.
Susan Paterson, fleet manager for a local company, had been heading home from work when she saw Mrs Evans' car coming straight at her.
She said: "As I looked ahead I saw a car. It came out into my lane and was coming straight towards me.
"It wasn't creeping, it was just coming at speed towards me. I remember thinking 'what can I do?' I thought 'it's going to hit me and I'm going to have to sit there while it does."'
She could not see anyone in the driver's seat, which "really freaked me out," she said.
The court heard how Mrs Evans had just exited a roundabout when she began driving on the wrong side of the road towards Ms Paterson's car.
The Vauxhall driver said the Peugeot "seemed to be slightly out of control."
Mr Vandyck said: "One of the unusual features of this accident was the deceased was moving in a manner shortly before it that was entirely out of keeping with her normal driving.
"We've also heard there were reasons for her to be tired and that Mrs Paterson couldn't see the driver of the Peugeot.
"Any one of these features suggests something unusual has happened to Mrs Evans before the accident.
"Her husband suggests she may have had a medical accident."
Dean Evans also told the inquest his late wife always drove fully upright and sat very close to the steering wheel, Mr Vandyck pointed out.
He said: "It appears the impact of the accident is explicable by the overloading of the other safety features because of the positioning of the pelvis on top of the anti-submarining device."
The VSC report found there had been a lack of interaction between Mrs Evans' pelvis and the anti-submarining ramp, and the airbag did not intervene effectively between her chest and the steering wheel.
The seatbelt alone was not enough to protect her and it let out a large length of webbing and did not stop her being thrown forward as much as would normally be the case, it said.
Dr Gloyns disagreed that Mrs Evans had been sitting in an odd position before the accident.
He said: "The whole picture is consistent with her sitting normally in the seat."
The three-day inquest was adjourned to tomorrow, when a Peugeot representative is due to give evidence.