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.

Perth to Shark Bay is now an EV Cruise.

Now that the WA EV Network DC charger at the Overlander Roadhouse is available to the public the biggest gap between DC charging on the Perth to Shark Bay drive is 228 kms, once the Billabong Homestead DC charger goes live that gap reduces to 182 kms. This makes the 848 km drive (to Monkey Mia) a comfortable one day drive during the daylight hours of winter, it also means a standard range model Y could drive that trip at the speed limit while keeping the battery level between 20% and 85%. Take note, there’s no harm to the battery by going below 20% the potential issue could be queuing at a regional DC charger with no sentry mode available.

Northampton WA EV Network DC charger

Below is a suggested plan for those in a standard range vehicle, if you have a LR or Performance use the same plan but with a lower charge percentage when departing each charging stop. Plan for 9 hours of driving plus 90 minutes of charging spread over 3 or 4 charging sessions.

Jurien Bay, peak charge speed 115 Kw.
If your trip is on the weekend or holiday period depart early. Although this trip can be done in daylight hours a 6.00am departure will pay dividends at the first charging stop in Jurien Bay. Why? Because humans are ruled by their stomachs, it’s a sure bet that on a Saturday morning or School holidays the Jurien Bay chargers will have a queue while the passengers stretch out morning tea. Trust me, you really don’t want to get stuck behind a couple of short range legacy EVs trickle charging to 100%. Get going early and get ahead of the grazing sheep.

Geraldton and/or Northampton, peak charge rate 115 Kw.
The next charging stop is Geraldton so 80% is plenty to cover the 200 kms. Once you get close to Geraldton you have a decision to make, do you bypass Geraldton and push on another 52 kms to Northampton DC charger thus avoiding some of the Geraldton traffic or play it safe and “Always Be Charging”? This is up to you depending on how busy you think Northampton could be, keep in mind Geraldton has the capacity to charge 4 EVs at once, Northampton it’s only a 2 EV site.

The drive from Northampton to the Overlander Roadhouse is the biggest gap of 228 kms, even at 110 kmh in poor conditions a standard range could still drive this on 65% battery but the trick here is to keep charging until the charging rate drops below 45 Kw, this will generally be at approximately 85% on a standard range battery pack. Why is 45 Kw important? That’s the average charging rate you’ll get at the Overlander on the WA EV Network 50 Kw DC charger.

Little Lagoon Shark Bay

The drive between Overlander and Monkey Mia may only be 154 kms but has caught out many impatient EV drivers in the past, it’s a sure bet that sometime after lunch a strong westerly will blow significantly reducing range, don’t get caught short, add 154 kms of range plus a 20% buffer so your not hypermiling into Shark Bay after dark.

Foot note: Lancelin has both Tesla Superchargers and a WA EV Network charger, this is an optional stop on the way north on potentially busy days or if you’re not in a hurry and don’t mind the total 13km detour. Be aware that if you take this option and bypass Jurien Bay you’ll need to add enough charge to drive 303kms to Geraldton.

Model Y Tyres: be one step ahead to keep the costs down.

I’m hoping the instances I’ve seen in the past week with regards to uneven tyre wear on 2023 WA based Model Ys is just pure coincidence rather than being widespread across the Australian fleet, in saying that it’s best to be prepared by spotting any uneven wear early and booking the vehicle in for a check and alignment.

How can you spot an issue early?

If you look at the tyre surface from the front or the rear it can be very deceptive, tyre wear may look very even across the tread and wear on the outer edge is fairly easy to spot. On the other hand wear on the far inside edge is almost hidden until it’s too late, that’s why getting a tyre rotation or inspection done 10,000kms after delivery is well worth the effort. Taking the wheel/tyre off and rolling it slowly while carefully checking the surface will show up any early signs of uneven wear.

Check the inner edges when the tyres are off.

Why bother?

If a looming safety issue doesn’t sway you to be vigilant maybe some basic arithmetic  will, a 19inch tyre on a Model Y that has even tyre wear throughout its life should survive for at least 50,000kms, if you don’t correct uneven wear early the tyre is likely unroadworthy at 30,000kms, that’s approximately $800 worth of tyre tread wasted. For those vigilantly counting every cheap kWh of electricity you charge your Tesla with you may be wasting more on tyres per km than you’re spending on electricity per km.  If you have a Model Y with higher priced Pirellis it’s closer to $1100 wasted.

Fitting new tyres

Hopefully you get even tread wear and a high km lifespan out of original set of tyres but eventually they’ll need replacing. Unless you can find a compelling reason to change brands I’d recommend sticking with a similar Hankook 19, Michelin 20 or Pirelli 21 that Tesla factory fitted, often keeping it simple is the best method.
Without doubt most Model Ys in WA will be fitted with 19inch Hankook Ventus EvoS1 (255/45/19) I recently got a quote for these at $499 each, that’s reasonable but I highly suggest you make enough phone calls to get not only a competitive price but a tyre shop that will respect both you and your car.
Hankook have also recently introduced a similar tyre specifically for Electric Vehicles called the Ion AS, in the 255/45/19 size I received a quote for $539 each.

I’m sure you’re asking this question; “Is an EV specific tyre marketing BS?” The answer will be revealed soon as one of our members is currently putting the Hankook Ion tyres through a thorough long distance test across the top end of Australia.

In summary:
Keep a constant check on your tyres, it only takes two minutes while the car is on charge.
Correct the reason for uneven wear ASAP.
Phone around for competitive tyre prices in the weeks before you need new tyres not on the day you find your car unroadworthy.

A Tale of Two Motors

Test Number 2

After seeing the results from test number 1, How much do 19 inch tyres and wheels improve the performance of a Tesla Model Y, it was decided to do a second 272 km test (along the same route) between the same Model Y Performance with 19 inch Gemini wheels and tyres and a Standard Model Y with exactly the same wheel and tyre set-up.

The clear difference between these two vehicles is their drive units. The Performance Y has dual motors with a maximum of 393kW power, whereas the Standard Y has a single motor producing a maximum 194kW. The Performance Y is 88kg heavier than its standard range stable-mate due to a combination of different-sized battery packs (and chemistry difference) and the extra weight of its additional motor. The operating parameters of the two cars were identical with tyre pressures set to 42 psi cold, air conditioners set to 22°C and the same number of occupants in each car. You can read in the initial test all the steps taken to obtain an untainted result.

Model Y
Performance
19″ Gemini
Model Y
Standard
19″ Gemini
Leg 1
31km
206Wh/km198Wh/km
Leg 2
105km
164Wh/km165Wh/km
Leg 3
105km
153Wh/km156Wh/km
Leg 4
31km
98Wh/km105Wh/km
Total
272km
157Wh/km158Wh/km

Test start 9.05 am, completion 12.42 pm. Weather, clear skies temp 13 – 20°C. Moderate wind from the same direction for the whole test which reflects in the result for Legs 2 & 3.

Please note the Performance Y once again recorded a total trip of 271 km over a 272 km journey, the other two test cars both recorded 272 km.

Although the Performance Y is heavier than the Standard Y and also has a second drive unit which slightly adds to mechanical friction losses, these disadvantages are likely compensated for by it being about 14 mm closer to the ground. Since reduced ground clearance enhances efficiency at higher speeds, a test in stop/start city conditions would likely slightly favor the Standard Model Y.

Which is the best Model Y variation?

First up the Performance, Long Range and Standard variations of a Model Y all have the major reasons to buy a Model Y in the first place: Excellent internal storage space considering its outside dimensions, good rear seat legroom, comfortable upright front seats, a high level of safety for occupants in a crash, all can legally tow 1600kg with trailer brakes, the most efficient pure electric drivetrain for its size and weight, and lastly but most importantly full access to the best and most reliable charging infrastructure in Australia, that being the Tesla Supercharging network.

The Performance Model Y
$101,564 on road in Western Australia (as of 17/02/2024)
Check Tesla website for current pricing
74.5kWh usable NCA battery pack
514kms WLTP
Genuine range on coarse country roads 408kms.

This variation has the additions of dual electric motors, performance brakes, slightly lowered suspension and a few cosmetic additions, it also has a track mode setting if you can find a safe controlled track to let the car off it’s leash.
The Performance is brutally quick when required, the brakes are extremely good and the 21 inch wheels with Pirelli Pzeros look fantastic. Unfortunately the 21s are the only wheel/tyre combo available, these consume a lot of energy. If you’re happy to drive in the Albany-Perth-Geraldton corridor the 21s are fine, if you have plans for long country trips away from reliable DC charging you will have to drive with a bit more caution.

Long Range Model Y
$86,484 on road in Western Australia
74.5kWh usable NCA battery pack
533kms WLTP
Genuine range on coarse country roads 464kms with 19 inch wheels

This variation is often referred to as the sweet spot; Dual electric motors, very good acceleration, the longest range battery and priced so it does receive some tax breaks for business folks. It also has the choice of 19 inch Gemini wheels or 20 inch Induction wheels ($2400+tax), the Induction wheels will reduce range slightly so my advice would be to option the Geminis and purchase a $300 set of Induction wheel covers for city driving and refit the Gemini hubcaps on long trips away from reliable DC charging.
My guess is the LR will outsell the Performance by a margin of 5 to 1 in Australia, especially to those that think range anxiety is real. If I lived in a WA country town or towed a trailer more than 1000kms on a regular basis I’d consider the Long Range Model Y.

Standard Model Y
$72,639 on road in WA
(eligible for $3,500 state Government rebate – if no options)
57kWh usable LFP battery pack (the Ricky Gervais pack)
455kms WLTP
Genuine range on coarse country roads 370kms with 19 inch wheels

Despite having good sales already in WA this rear motor only variation is still massively misunderstood amongst the public, it may be the “slowest Tesla ever” with a 0-100kmh time of 6.9 seconds but the critically importantly 80-120km acceleration is plentiful. It may have the smallest capacity battery pack but it’s LFP chemistry means the battery pack is far more flexible, the LFP is very happy being charged to 100% on a weekly basis (even daily if you “just don’t care”), it may not charge faster than 170kW like the NCA packs but the LFP has a flatter DC charging rate that is less confusing to new owners.
Take note: The three fastest pure EV trips around Australia took 14, 16 and 17 days. All completed in Standard Range Model Ys.

As each month passes and reliable DC chargers installations increase around Western Australia the more the Standard Model Y will be able to travel without compromise. If you live in the Perth-Albany-Augusta triangle and don’t care about brutal acceleration or all wheel drive traction the Model Y Standard is the best choice of the 3 variations.

How much do 19 inch Gemini Wheels and Tyres improve the Energy Efficiency of the Model Y Performance?

The only way to correctly test energy efficiency is by having two similar cars driven on the same roads at the same time over a reasonable long distance.

This test was conducted using two almost identical 2023 White Model Y Performance vehicles built in the Shanghai factory within days of each other. Both had covered over 1,600kms in the first week of ownership. Both had aircons set to 22°C. Both had cold tyre pressures of 42psi. Both had two occupants. It is crucial to note that neither car used the Williams Supercharger to navigate to and thus battery preconditioning was NOT used to avoid contaminating the results. During the test, the cars were driven no closer than 60 metres at highway speeds with the biggest gap being approximately 400 metres. Each car drove the front position for half the journey.

Cars were driven at the speed limit (max 110km/h) as much as possible with overtaking of slower traffic only conducted on designated overtaking lanes. Luckily traffic flow was generally good during the whole test.

To be clear, the test was conducted mostly on the Albany highway, a coarse road surface that’s consumes plenty of energy and is often used by Tesla drivers visiting the Great Southern.

Over the total 272km test (136kms south, 136kms north), the Performance model Y with factory fitted 21 inch Überturbines averaged 178Wh/km while the Performance model Y with the 19inch Gemini rims and hub caps (acquired from a new standard range model Y) averaged 158Wh/km, an improvement of 11%. That’s not a typo, that’s eleven percent with every other aspect of the two cars being identical.

There’s two main factors that cause the difference in energy efficiency: The 21inch Überturbines have what could be described as “sticky” Pirelli tyres, great for putting down the power and torque of the dual electric motors under extremely hard driving, but energy hungry in general driving. The 21 inch wheel/tyre combo has less smooth tyre surface and more rough wheel surface on the outside of the car. The Gemini wheels have more smooth tyre surface and a fairly smooth hub cap so airflow at higher speeds is less interrupted. If you’re a City Slicker, the 21 inch Uberturbines are fine. If you plan on long distance driving away from reliable DC charging, the energy wasted may be an issue.

Model Y
Performance
21″ Überturbines
Model Y
Performance
19″ Gemini
Leg 1
31 km
212Wh/km195Wh/km
Leg 2
105 km
168Wh/km149Wh/km
Leg 3
105 km
200Wh/km175Wh/km
Leg 4
31 km
105Wh/km95Wh/km
Total
272km
178Wh/km158Wh/km
TOCWA Note: Distance per Leg is approximate
  • Leg 1: Byford to Albany Hwy T junction. Moderately uphill, average speed 64 km/h
  • Leg 2: T junction to Williams Woolshed Supercharger. Moderately downhill, average speed 97 km/h
  • Leg 3: Return Williams Woolshed to T junction. Moderately uphill, average speed 102 km/h
  • Leg 3: T junction to Byford. Moderately downhill, average speed 71 km/h

Conditions: dry 22°C to 29°C, light winds. Start time 9.30 am, finish 1.15 pm.

Überturbines (left photograph), Geminis (right photograph). Both “Since Charge” screens did not reset to zero as per normal after Supercharging???

This test was conducted by Harald Murphy and Rob Dean, two of the most experienced long distance drivers in Australia.