Diesel vs EV Across the Nullarbor, Which is Cheaper in Fuel?

The best comparison is to use two vehicles that are likely to drive across the Nullarbor on any given day. I know a few dozen Tesla Model Y SUVs have done it, including my own 4 times, and I also have no doubt a similar size 2022-24 Hyundai Tucson diesel SUV has more than once crossed the country.

The Journey
The section between the towns of Ceduna in the east and Norseman in the west is generally seen as the Nullarbor drive, a total distance of 1201kms, a sealed surface, 1 lane each way, mostly flat, virtually all 110kmh.

The cheapest fuel in the middle section of the Nullarbor is $2.52 per litre (March 2024).

Driving the Hyundai Tucson Diesel
The claimed fuel consumption for the 1.6 litre diesel is 6.3 litres per 100kms. Our Hyundai driver is very experienced at getting the best fuel consumption so I’ll round that down to 6 litres per 100kms, it also makes the arithmetic a bit easier. The Hyundai driver is also wise with his fuel purchases and will make use of the 800km range fuel tank by filling right up on the cheapest fuel in Ceduna at $1.96 a litre.
Despite the good range per tank the Hyundai driver still needs to stop for fuel once between Border Village and Caiguna Roadhouse, luckily there are 6 different fuel stops on that 350km section. According to this week’s diesel prices the cheapest is Eucla at $2.52 a litre, luckily the Hyundai driver doesn’t need to fill up, it’s only necessary to add 400kms of fuel or 24 litres, enough to scrape through to Norseman.
Ceduna 48 litres at $1.96 = $94.08
Eucla 24 litres at $2.52 = $60.48
Trip total for diesel $154.56.
Why not use the cost to refill at the end of the trip instead of the start? Norseman diesel has averaged $2.14 during 2024, that would cost more, the Hyundai driver is smarter than that.

The EV SUV Using March 2024 Charging Options
My Model Y has averaged 15.3kWh per 100kms over the past 43,000kms, so to make the arithmetic easier I’ll round that up to 16kWh per 100kms.
At 16kWh per 100kms the Model Y range is limited to 460kms, this requires a minimum two charging stops after the initial charging at Ceduna. To make the journey without any compromise I’ll go for a more expensive 3 charging stops at Nullarbor, Mundrabilla and Caiguna. Despite paying a flat all you can charge fee of $32, $30 and $50 respectively I’ll only be adding 65-70% to the battery at each stop.
Ceduna 48kWh x 60 cents per unit = $28.20
Nullarbor flat fee $32
Mundrabilla flat fee $30
Caiguna flat fee $50
Trip total for electricity $140.20.

The EV SUV Using July 2024 Charging Options
From July onwards DC charging options will improve rapidly on the western side of the Nullarbor with 4 Horizon sites powered with solar energy. Any improvement on the eastern side of the Nullarbor in Q3 2024 will depend on the NRMA following through on another media release claiming the Nullarbor and Border Village Roadhouse will be getting DC charging soon, if that happens all fast DC charging from Ceduna to Norseman will be 60 cents per unit making the arithmetic easy.
192kWh x 60 cents per unit = $115.20

Unfortunately for the diesel vehicle owner there’s very little hope for an improvement in fuel costs, 5 competing fuel suppliers at 11 fuel stops are burdened with transporting fuel over long distances adding to the expense. On the other hand EV charging has two aces up its sleeve, first and foremost electricity can be made on site at a reasonable cost with renewable energy, a good example is the Horizon DC chargers being installed in remote areas of Western Australia that are solar powered. Secondly EV charging in Australia is still in its infancy, competition is yet to arrive.

The Horizon Power WAEV Network charger at Norseman is 60c/kWh.

Is a Tesla more efficient in Summer? Yes but it’s a two edged sword.

The climate in the southern half of Western Australia is near perfect for a Tesla, warm and dry most of the time and winters where the temperature only drops below 5C for a few hours on the occasionally early morning, if you enjoy getting good Wh/km efficiency WA is the place to achieve it.

On the downside is the long hot summer of constant intense sunlight and high temperatures, this doesn’t generally harm the Wh/km figures recorded during longer drives but does put a serious dent in efficiency for those driving short (less than 15km) trips after being parked in an exposed area for even a short period during the day. Every time you drive off in a car with a hot interior the aircon is working hard to reduce the temperature, depending on conditions that could take anything from 10 to 30kms.

Teslas have an excellent feature known as cabin overheat protection, even on a 30C day this will consume up to 4% of the battery over 9 hours, personally I’ll happily accept a 4% loss each day over Summer but anyone who is not is free to turn cabin overheat protection off. Of course if car park designers who have a fetish for destroying trees allocated funds for solar panel canopies car parks wouldn’t be so hot.

So are all these hot Summer days killing your range?
Not really, it’s consuming far more energy between each charge but as this is caused by short drives and long parking sessions it’s not relevant unless you’re buying expensive electricity. Range is only a factor on very long drives away from reliable fast charging. When you go on a long drive the heat will have little effect on your Wh/km efficiency (it helps if you pre-cool the interior while plugged into shore power before departure).

Hot tips for a cool interior
Try to park in the shade even if it’s a 200 metre walk to your destination.
Get interior shades up, especially over the black dashboard.
Pre-cool the interior using the phone app about 5 minutes before arriving at your car.
If only parking for 45 minutes or less put the car in “keep” mode, this leaves the air-conditioner on and does not use any more energy than letting the car heat up then cooling it down again.

Supercharger tips

The most recent Tesla Superchargers in Karrinyup, Williams and Margaret River are V3, the 2017 built Eaton Superchargers are V2. Those who’ve charged at Eaton will have noticed each charging stall has two cables, the second cable is a retrofitted CCS2, that’s the one 99.9% of WA Tesla owners will use. V3 chargers are vastly superior as each stall is capable of delivering up to 250kw depending on the vehicle battery type and size, starting percentage and battery temperature. The V2 stalls at Eaton have a maximum output of 145kw for each pair of stalls (1A&B, 2A&B, 3A&B), meaning if you plug into stall 1B not long after a car has plugged into 1A your initial charging speed will be very slow. The trick is to avoid parking next to another car if possible. The slower charging speeds at Eaton are only a nuisance on busy Saturday mornings on a long weekend. To get the best charging speed set navigate to the Supercharger and the car will automatically preheat the battery pack before arrival, on cool days this makes a significant difference to the starting charge rate. A second tip for the fastest charge rate is to arrive with approximately 10% range and depart with 60-80% depending on the distance to the next chargers. Arriving with only 10% is advice I would never give with any other type of charge point in Australia, the fact is Tesla Superchargers are vastly more reliable than any other DC chargers in this country.

Eaton Supercharger cables.

Why not charge to 100%?

Basically 80 to 100% takes longer than charging from 10 to 60%, wasting time defeats the main purpose of a Supercharger. Be aware that when a Supercharger gets busy charging may get limited to 80%, the phone app will provide a notification, if charging past 80% is absolutely necessary it can be overridden. You can read more here: Charging to 100% is a waste of time.

Don’t overstay you visit- Once your car has completed charging you have 5 minutes grace to move the car, failure to do so will result in a backdated per minute surcharge added to your Supercharger account, as the phone app will pre warn you there’s no excuse.