PC James Dixon, the police officer who died, was off duty at the time and riding a motorbike.
He has appeared on Sky One's popular reality show, Road Wars.
Thames Valley Police Chief Constable Francis Habgood said: "My officers, staff and I were devastated to hear the very sad news about our colleague PC James Dixon, aged 39 and the 91-year-old woman who died as a result of a road collision yesterday (5/12)".
The IPCC said PC Dixon was on a training exercise and was not responding to an emergency or pursing the vehicle he collided with.
Dixon was on duty and riding a motorcycle. when it was involved in a collision with a vehicle.
Tributes to PC Dixon have been posted in comments on Thames Valley Police's Facebook page, with many referring to watching him on the Sky 1 TV series Road Wars. The next-of-kin of both people have been informed. "It was a real pleasure to know you and my heart goes out to your family and loved ones". It's well respected officers like PC Dixon that inspire me to be a Police Officer.
Pc Dixon was based at Loddon Valley police station on the outskirts of Reading.
A 91-year-old female passenger of the auto also died, while the vehicle's driver went to hospital with injuries which were not thought to be life threatening. Her injuries are not thought to be life threatening.
"My thoughts and sympathies are with their families and friends and the colleagues of the officer at this very hard time".
Tributes have been paid in Parliament to a police officer who died in a crash with a auto while on duty in Berkshire.
IPCC Associate Commissioner Guido Liguori said investigators were attending the scene as part of an "independent investigation to determine the circumstances which led to the collision".