Using Tasmania specific data, the RACT Vehicle Operating Cost survey calculated all expenses associated with normal car ownership including purchase price, interest, fuel, electricity, servicing, new tyres, insurance and depreciation, to allow buyers to compare vehicles across all classes.

RACT general manager mobility services Darren Moody said at $109.97 a week the Rio in the light class was cheaper than all the vehicles in the micro class.

"[The Rio was] more than $17 per week [cheaper] when compared to the Fiat 500 in the micro category," Mr Moody said.

"It's a really good buy.

"Keen ongoing drive-away prices for the vehicle are largely responsible."

Running costs for an electric vehicle dipped below $200 a week for the first time, the survey found.

"That's comparable with a mid-size SUV," Mr Moody said.

The survey found, although SUVs now outsell passenger cars in Australia, there is a premium in purchasing an SUV over a standard passenger car.

Mr Moody said if you compared a Hyundai Kona, the leading vehicle in the small SUV category, with the Kia Cerato, which leads the small car class, motorists would pay more than $6,500 extra over a five year ownership period.

The survey found there were reductions in interest rates and servicing costs over the last year, fuel and tyre costs remained at a similar level, while depreciation costs increased slightly.

"The RACT Vehicle Operating Costs survey gives you what you need to know before you step into a car showroom," Mr Moody said.

"When you are buying a car, the price is just the start of the spending.

"There are hidden costs which you should consider by doing your research and asking the dealer questions about on-road costs."

This year the survey studied 140 popular vehicles across 14 categories.

Calculations are based on private ownership for five years and driving an average 12,000 kilometres per year.