Diesel – fuel for thought

In the third part of our Fuel series, we look at diesel.

diesel pump at petrol station

Are diesel cars more fuel-efficient?

As price-pressured motorists look to get more bang from their buck, sales of diesel light vehicles have increased rapidly over the last couple of years.  Due to lower fuel consumption rates than an equivalent petrol engine, diesel engines are the standard in heavy vehicles. So why not in light engines too?


  • Modern diesel engines are as quiet, smooth and powerful as petrol engines and are more fuel-efficient.


  • One disadvantage often mentioned by NRMA Members is that diesel handpieces at garages often have a film of diesel fuel over them, as any spillage does not evaporate as quickly as petrol.  And if the diesel gets on your hands or clothing, the smell is difficult to remove. Retailers are making efforts to avoid this but have not yet found a perfect system.


  • Diesel fuel does not contain more energy than petrol. In fact, it contains marginally less.
  • Whereas the intake of a petrol engine has a throttle blade in it, which forms an obstruction and reduces efficiency, a diesel engine doesn’t. Therefore, it gets lower fuel consumption.
  • Diesel variants are often more expensive to purchase than the petrol ones, so if your interest is purely in lower running costs, make sure it is going to make sense for you by checking out the NRMA’s Car Operating Cost Calculator.
  • In many cases, the higher initial purchase cost outweighs the reduced fuel cost.  But you are also gambling on the price of diesel staying similar to petrol over several years.
  • If you have never driven a diesel-engined vehicle and are considering purchasing one, you should test drive a few to see how it feels.

If you drive a diesel car, do you feel you’ve you got your money back in reduced fuel/servicing costs?  And are you happy with the driving characteristics of diesel?

Ethanol in petrol – is it ok for my car?

This is the second blog in our series on Fuels.  In the first blog we looked at premium fuels, now we take a look at ethanol in petrol (E10 and E85).

ethanol in petrol

Does an ethanol petrol blend affect the performance of your car?


E10 is standard unleaded petrol (ULP) with 10% ethanol added. Expanded use of E10 is a strategy endorsed by the NRMA Board and aims to encourage the take-up of ethanol – which is locally produced and reduces Australia’s dependence on fossil fuels. Straight unleaded is now getting harder to find.

Vehicles built pre-1986, some post-1986 vehicles, most small engines such as chainsaws and whipper-snippers and most Japanese motorcycles are recommended NOT to use ethanol. These vehicles and power tools will have to use premium petrol when ULP becomes unavailable.

Motorists whose vehicles cannot use ethanol should be aware that all petrol distributed by United contains ethanol except its Premium 98. View a list of all petrol grades available in NSW.

The octane of E10 is commonly 93-94, so motorists whose vehicles are specified for 95 octane fuel should be cautious using E10. If you want to try E10 check that there are no unusual noises like rattling or pinging under acceleration, which is a sign that the octane is too low.  United claims its E10 is 95 octane.

Check whether your vehicle is suitable to use an ethanol petrol blend.

A refuel of 50 litres at a price difference of 10 cents a litre between E10 and premium would cost an extra $5.   But this has to be kept in perspective with the overall cost of running a vehicle.


You should not use E85 in any vehicle that is not designed for it. The only cars designed for E85 are the current model Holden Commodores that are so marked and the Saab Biofuel range.  For other vehicles, check the recommendation in the owner’s manual or check with the dealer or manufacturer and adopt their recommendation.

In our next blog, we’ll take a look at Diesel.

Do you use an ethanol petrol blend in your car? What affect has it had on your car’s performance and reliability?

Petrol grades currently available in NSW*

Company Fuel Name Research Octane Number – RON
7 Eleven Unleaded 91 91 ULP – Unleaded Petrol
Premium unleaded 95 95 Premium
Premium unleaded 98 98 Ultra Premium
Unleaded E10 93-94 ULP +10% ethanol
Diesel N/A Diesel
BP Unleaded 91 91 ULP
Unleaded 95 95 Premium
BP Ultimate 98 Ultra Premium
e10 Unleaded 93-94 ULP +10% ethanol
Diesel N/A Diesel
Shell/Coles Unleaded 91 ULP
Premium 95 Premium
V-Power 98 Ultra Premium
Unleaded E10 93-94 ULP+10% ethanol
Diesel 10 N/A Diesel
Caltex/Woolworths Unleaded 91 ULP
Vortex 95 95 Premium
Vortex 98 98 Ultra Premium
E10 unleaded 93-94 ULP+10% ethanol
New Generation Diesel N/A Diesel + 2% biodiesel
Bio B5 N/A Diesel + 5% biodiesel
Bio B20 N/A Diesel + 20% biodiesel
E85 100+ ULP + up to 85% ethanol
United Petroleum Plus ULP 95 ULP+10% ethanol
Boost 98 98 Premium +10% ethanol
Premium 98 98 Ultra Premium
E85 (only available in Rozelle) 100+ ULP+ up to 85% ethanol
Diesel N/A Diesel
Liberty Unleaded 91 ULP
e10 Unleaded 93-94 ULP+10% ethanol
Premium unleaded 95 Premium

*not all available at all sites

Fuels – which should you use?

petrol pump

Which premium unleaded fuel do you find the most efficient and cost effective?

Motorists can be forgiven for being confused about the fuels available and what their car needs.  There are five types of petrol now available (standard unleaded, 95 premium, 98 ultra premium, E10 and E85) as well as Diesel and LPG.

This blog is the first in our series on fuels to help clear up the confusion about which fuels are the best to use. We begin with premium unleaded.

Premium Fuels – is there a benefit?

Petrol vehicles are designed for a specific octane fuel and normally do not benefit from using higher octane fuel.

If the manual says you can use more than one type of petrol or blend, you may get the advantage of reduced fuel consumption (but only if your vehicle’s engine automatically adjusts its parameters to take advantage of higher octane).  Conversely, you may be able to save money by using a lower octane fuel, if the manufacturer states the vehicle will run normally on it.

As a rule of thumb:

  • 95 premium can give around 4% lower fuel consumption than 91, assuming the engine computer adjusts to take advantage of the octane difference.
  • 98 might give 3% reduction over 95, again assuming the computer adjusts the engine parameters.

The overriding recommendation is to consult the owner’s manual for your vehicle and use fuel of the octane listed.  Some motorists report lower fuel consumption using higher octane fuel.  If you wish to check this for yourself, be sure to record your fuel consumption for at least 10 tanks before you make the change, so you have a good baseline.  Try and check your baseline under normal conditions – if you have an unusual country trip in the middle of your test period, for instance, it will result in atypical figures.  Conversely, if your driving is normally on highways, a week of city driving will bias your figures.  Then change to the higher octane fuel and do a check for the next 10 tank fills and compare the figures.  If the savings from any reduced fuel consumption are outweighed by the extra cost of the premium fuel, it is obviously not economically sensible to use the higher octane.

In our next blog, we’ll look at ethanol in petrol (E85 and E10).

Which premium unleaded fuel do you find the most efficient and cost effective?

Petrol prices continue to rise (Updated – 31 March)

petrol pump

Motorists should brace themselves for petrol prices up to $1.50 per litre.

Petrol prices have been steadily increasing in the last few weeks and are predicted to reach a two-year high of $1.50 per litre in the coming weeks.

Despite the high prices, research done by the NRMA have shown there are times during the week when petrol prices drop.  Saturday morning is the cheapest time to buy, and Monday afternoon is the most expensive.

Savings can be as high as 10c to 12c a litre between the most expensive and the cheapest, so it’s a good idea to keep an eye on daily petrol prices and try to buy when prices are low.

UPDATE: Petrol prices are now heading for $2 a litre and families should start saving money now.

An NRMA BusinessWise analysis found $2 a litre would add almost $2500 to the annual petrol bill for a Toyota Hilux driver from Penrith to the CBD, and $2000 for a Ford Falcon driver. A Campbelltown family with a Holden Commodore Berlina would pay an extra $1700 and $2210 if they lived in Gosford (via Daily Telegraph).

How have the higher petrol prices changed your driving habits? Do you seek out the cheapest petrol prices or just fill up when you’re running low on fuel?