The private sale premium is real, but it is smaller than most sellers expect once tax, time and risk are counted properly.
The genuine price gap
Across most mainstream vehicles the gap between a fair trade figure and an achievable private price sits in the thousands rather than the tens of thousands.
On prestige and low-volume vehicles the gap widens considerably, because dealers price in the risk of holding a car with a narrow buyer pool.
The stamp duty offset
In several states, trading against a new vehicle reduces the amount on which stamp duty is calculated. That is a direct, immediate saving a private sale cannot replicate.
It rarely closes the whole gap, but it should be included in the comparison rather than discovered afterwards.
Time, exposure and risk
A private sale means advertising, fielding enquiries, managing inspections and test drives with strangers, and handling payment and transfer safely.
There is also statutory and disclosure risk. A trade transfers that entirely to the dealer, which for many sellers is the deciding factor.
The third option
A managed sale sits between the two: your vehicle is presented, marketed and negotiated professionally, and you retain the retail upside without running the process personally.
It suits vehicles where the private premium is genuinely large enough to justify a proper campaign.