Father-of-two Darren Mark Harvey, 25, of Portsmouth Road, Woolston, died in the crash in the New Forest in August.
The coroner concluded Mr Harvey died as a result of a road traffic collision and it was probable that he steered into the vehicle in a deliberate act.
He said he could not be absolutely sure Mr Harvey had intended to kill himself.
The crash happened on the A337 close to the Holland Wood Campsite near Brockenhurst late on Saturday 22 August last year.
Mr Harvey's wife, Rebecca, told the inquest that on the night of his death, Mr Harvey had left home in such a distressed state, she had called the police.
The inquest was shown footage from a camera mounted on the dashboard of the fire engine that showed Mr Harvey's car swerve into its path.
He had a history of depression and was on anti-depressants, the inquest was told.
Mr Harvey's family described him as a "proud dad, a loving son, brother and grandson who recently married".
A man who died in a head-on collision with a fire engine probably steered into the vehicle deliberately, an inquest has heard.