Your questions answered: Why are smaller wheels more economical on EVs?

Electric cars are a hot topic again in this week’s carsales mailbox, and it’s the sweet spot of the market currently dominated by Tesla that’s generating so much interest.

We’ve also got one reader wanting to know about towing restrictions with the Subaru Outback, while others are asking about the spaciousness of the Mazda CX-9 and what might be the best small car – whether new or used – in the $20,000-$25,000 price bracket.

Question:

Answer: It’s not so much the diameter of the wheel but the rubber, tread pattern and width of the wheel. EV manufacturers typically have a more fuel-efficient wheel and tyre combination that helps make the predicted electric driving range figure that little more attractive.

Once you get into higher performance variants (not relevant for the I-PACE, but it is for many other EVs) or models with more aggressive tyres then the emphasis changes somewhat to grip and other performance parameters.

Those higher performance tyres typically compromise on rolling resistance – which requires energy to overcome – and instead ensures there’s more grip.

Also, in some instances the larger diameter wheels will be slightly wider, which not only adds some rolling resistance but also means pushing more air out of the way.

Question:

Answer: Most EVs have a nickel manganese cobalt battery, but some – including rear-drive Tesla Model Y and Model 3, the entry-level Ford Mustang Mach-E and the BYD Atto 3 – have a lithium ferrous phosphate, or LFP battery. Both NMC and LFP batteries are still referred to as lithium-ion batteries, but they have very different chemistries.

In short, NMC batteries can hold more energy, so can be slightly smaller and lighter to contain the same amount of energy. LFP batteries are cheaper to manufacture but you’ll need more of them to achieve the same range.

NMC batteries also don’t like being regularly charged up to their maximum 100 per cent state of charge. That’s why most EVs with an NMC battery have a function that allows owners to set a charging limit (usually 80 per cent) for everyday driving. Then they can fully charge before a longer road trip.

LFP batteries are almost the opposite. For longevity, it’s best to top them up to 100 per cent regularly. Tesla also recommends keeping the car plugged in and charging if you’re leaving it for a week or so.

So with your Atto 3, try to top it up to 100 per cent as often as possible.

Question:

Answer: The Ford Mustang Mach-E is certainly a pricey machine, although at least the entry-level model slides in below the $84,916 luxury car tax (LCT) threshold that allows it to take advantage of the FBT expedition on offer by the government.

As for others, Toyota has already warned the bZ4X will be expensive. While we don’t know how expensive, early indications are that it would be at the upper end of your price range, possibly more. Similarly with the Subaru Solterra, although Subaru is only taking the dual-motor versions (Toyota will likely get 2WD models too), which could be slightly more expensive.

VW is one that looks like it could get more serious with the Volkswagen ID.4. The company has already suggested a starting price around $60,000. Given the Skoda Enyaq shares much of the ID.4 underpinnings, we wouldn’t expect them to be miles apart on price.

Question:

Am I missing anything is there anything else that you think I should look at? – Dan M

Answer: I wouldn’t be calling the base Hyundai IONIQ 5 and Kia EV6 slow. Certainly slower than the dual-motor versions but still able to zip around respectably. Getting hold of them can also be a challenge given the relatively low numbers of them coming into the country.

As you’ve figured out, the Tesla Model Y offers the best all-round package. Decent space and, in Long Range guise, no shortage of thrust. Also has an awesome sound system and the bonus of being able to use Tesla chargers. I’ve found real-world range on a Model Y RWD to be close to 400km, so around 10 per cent less than the WLTP claim. The Long Range obviously has a bigger battery, so our expectation would be real-world range of about 450-480km.

Keep in mind, though, that as with the Kia and Hyundai, the Model Y LR uses an NMC lithium-ion battery, so the recommendation for everyday driving is to only charge to 80 per cent (leaving a full charge for longer road trips).

As for other options, there’s nothing that really stands out. The Ford Mustang Mach-E has promise but is expensive, and we’re yet to spend time with it.

Question: We bought a Mazda CX-5 2018 after listening to a good review by yourself and are very happy with it. Looking to upgrade for more legroom for my husband so we’re looking at a CX-9 GT, they will charge us about $65,000. Is this a good car or is there anything much better in this model/price category? Also, do you know anything about the car care packages they offer such as protectant for the paintwork/interior etc? – Natha D

Answer: I don’t think you’ll get much more legroom in the Mazda CX-9 compared with the CX-5, at least from the driver’s seat. Certainly, in the back seat the CX-9 will have more legroom, but up front there’s not a whole lot of difference.

The CX-9 is good buying, although its four-cylinder turbo engine can be thirsty. Also keep in mind the CX-9 is about to be discontinued. In the quest to head upmarket Mazda is effectively replacing it with the CX-80, which will be much more expensive. The CX-90 will be even bigger and pricier.

Check out the Kia Sorento and Hyundai Santa Fe as alternatives, although again there may not be much more in the way of front seat legroom. See our recent Best Family SUV 2023 mega-test for a comparison between the six of the top models in the family SUV class.

Question:

Answer: Subaru is very conservative with advice around towing. The company also recommends, for example, that people don’t tow at speeds above 80km/h, which could get frustrating on wide, open expanses.

As you point out, the company also recommends not using load distribution hitches. We asked for an explanation from Subaru and was told that such hitches can change the way weight is distributed on the car, potentially creating other issues. The engineer we spoke to said it was preferable to have the natural load and ensure the trailer is currently balanced.

Keep in mind electronic trailer brakes can also help with trailer sway. While they’re not legally required until you’re towing more than two tonnes, you can use them on any trailer. They allow you to brake the trailer independently, in turn effectively pulling it back and helping eliminate sway.

Also take a look at our recent tow test on the new turbocharged Subaru Outback XT to see how it goes when hitched up with a 2000kg tandem caravan.

Question: We’re looking for a small car to lower running cost car in tandem with our current family car (no need for two big cars). And dare I say bring a bit of sensibility back to the Australian boom in increasing car size.

The nuts and bolts of it, as concise as I can put it: My wife drives the family car, an Isuzu MU-X (there’s four of us). We’re in our early to mid 40s. We live in the Margaret River region south of Perth. Not ready to go into the EV market or variations of this with a budget at the top end of $20K to $25K. Despite the growing push and inevitable conversion. The small car will be driven around mostly paved roads, some gravel. And some 600km round trips to Perth and other regional centres from time to time.

Our two cars will be swapped around depending on who needs what at the time. But the small car will need to take up to the four of us and general gear from time to time. Who knows where my daughters will be at in eight years, but I’m thinking they could take over our small car. Or someone else in that first car market. Hence I’m thinking a new car is a better bet in this current time?

I’ve been thinking about the Mazda2, Kia Rio, Toyota Yaris… Hyundai…

With these parameters and without really being able to road test the smaller cars with the whole family etc. and not having driven any for a long time, will I be pushing the limits of a small car with my requirements?

New vs used: I get the impression this has switched from a used car being the better bet in previous years with depreciation etc but now a new buy is comparable. With better outcomes buying new now for resale later and getting to a point where the market brings the price of EVs down and increased selection in the next decade or so.

Answer: Firstly, let’s tackle the issue of loading up a small petrol-powered car versus an EV. The petrol model is more likely to experience a drop off in performance with the additional weight, whereas the EV’s torque will mask that slightly.

As for a car for you… Kia and Hyundai are great brands to start with, especially as each often has a full-size spare wheel, which would be a handy backup on those gravel roads. But with their entry-level (smaller) models they tend to be space-savers. Still, the Kia Rio is a great car, albeit without much in the way of country road grunt. Or you could sit up a tad higher in the Hyundai Venue, which should just hit your budget.

A more spacious alternative would be a second-hand Subaru XV (it’s recently since been replaced by the Crosstrek). It’s also a handy thing for light-duty off-roading.

Regarding used car values, the lack of supply in the new-car market over recent years has certainly reduced the depreciation on new cars. But don’t expect that to last. The market is vaguely getting back to normal and once you start seeing more discounting entering the market then that makes near-new used cars less attractive.

As for the CO2 regulations due to be announced later this year, we wouldn’t expect them to impact used vehicles. Expect the focus to be on greening the new-car fleet.

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