Turners Auctions predicts greater demand this year for small vehicles because of petrol prices.
The retail price of petrol is poised to break $2 per litre for 91 octane for the first time in more than two years. The retail price for 95 octane is already $2.06.9 per litre. Diesel is about $1.36 per litre.
Turners Auctions says sales for small cars rose by more than one percentage point between October - December.
Chief executive Graham Roberts says increased demand is also likely to push up the price of smaller vehicles.
The Automobile Association says it has received hundreds of calls over the past month from people thinking about downsizing. It says fuel prices are expected to climb further.
BP says the price of imported oil has gone up 4 cents per litre since 5 January.