Analysis: efficiency has become the big selling point for electric cars which means we'll be able to travel longer distances on one charge
If you are considering an electric car, you will likely have seen the term 'efficiency' front and centre in most marketing materials and reviews. Manufacturers are currently spending hundreds of million of euro to achieve single digit efficiency gains. This is because a more efficient vehicle can travel further using a smaller battery pack. Customers demand a certain level of range in their vehicles and if a manufacturer can achieve this using a smaller battery pack, it can greatly improve their profits.
The battery pack is both the most expensive and the heaviest part of an electric car. In addition, a more efficient car will cost you less per week to charge, put less demand on the electric grid, generate less CO2 in use and be kinder to the environment in the manufacturing stage of its life. A more efficient electric car is better all round, and it is now easier to understand why staggering levels of research and development resources are chasing minute efficiency gains.
From RTÉ Radio 1's Brendan O'Connor Show, motoring journalist Geraldine Herbert on electric cars and how to avoid 'range anxiety'
If you have been driving a car for more than 10 years, you will likely consider your vehicle's efficiency in terms of miles per gallon, how far your car travel while burning one gallon of fuel. This is a good example of how we strangely hang on to imperial measures long after they have officially been retired from our systems. Similarly, you may consider your own height in feet and inches, but all other measurements of length in metres.
Younger drivers are more likely familiar with litres of fuel used to travel 100km. An efficient small car may reach 6L/100km, or to use the old measure, 47.1 miles per gallon. But electric cars use electric energy that is transformed to mechanical energy. No liquids are involved, so a different measure is needed. Watt hours per kilometre, or Wh/km, describes how much electrical energy your vehicle will use to drive one kilometre. The higher this number, the more electricity your car will use on its daily commute and the less range you will get from one charge.
As manufacturers rush to bring more electric vehicles to market, many are based on models that were originally designed to be powered by internal combustion engines. This has allowed manufacturers to use existing chassis and production lines to speed up their move towards electric vehicles. However, a vehicle that has been converted to work with an electric drive train will typically not perform as well as one that has been designed from the ground as electric.
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From RTÉ Radio 1's Ryan Tubridy Show, Cliodhna Lyons from Nissan is the person who will decide what kind of car you're going to be driving in 10 years' time.
One example is the now discontinued VW e-Golf, where a traditional Golf was converted to electric. This allowed for a relatively small 32kWh battery (190km range) when compared to its later iD3 sibling, which was built on a dedicated electric platform and boasted a 77kWh battery (450km range).
A dedicated electric car will have better battery placement and typically more space for a larger battery pack. Packaging for the motors will also be optimised leading to more interior space and allowing for better aerodynamic design. This is important because the amount of energy that a vehicle uses as it pushes through the air is one of the biggest factors in terms of overall efficiency.
This is very clear when we consider one of the most efficient EVs that will soon come to market, the Hyundai Ioniq 6 (which will be launched in Ireland in late 2023). In its most efficient trim, it boasts an exceptional 150kW/km from its 74kWh battery. One of the main factors that allows the Ioniq 6 to achieve this level of efficiency is its ultra-low drag coefficient of 0.21.
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From RTÉ 2fm's Jennifer Zamparelli show, motoring journalist Michael Sheridan answers listeners' questions on electric cars
The impact of drag is clear when we compare the very sleek Ioniq 6, to its more blocky cross-over sibling, the Ioniq 5. Both share the same chassis, motors and battery chemistry. The main difference between the two is how much energy they use to push through the air. This is reflected in the Ioniq 5's drag co-efficient of 0.288. Even though this is one of the best drag co-efficients in its class, it is still substantially more than the slippery 0.21 of the Ioniq 6. In every day use this means that the Ioniq 5 will need to recharge after 390km, while the Ioniq 6 using the same amount of electrical energy, will manage 475km before it needs to recharge.
Interestingly we can also compare within models and see how larger battery packs can impact efficiency. While a larger battery pack will allow a vehicle to store more energy, it will also cause a vehicle to use that energy in a less efficient manner due to the increased overall mass.
Look at the 2 wheel drive versions of the Ioniq 6 and you can see that the larger battery version with a 74kWh battery reports an efficiency of 156 Wh/km, while the smaller battery pack 54kWh version has a slight efficiency advantage of 150 Wh/km. This shows that mass and aero can drastically impact a vehicles range.
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From RTÉ Radio 1's Morning Ireland, Brian Cooke from the Society of the Irish Motor Industry on the growing popularity of electric cars
Larger and heavier vehicles need far more energy and this requires large batteries to ensure suitable range. For example, the 2023 Audi SQ8 e-tron Sportback returns a relatively poor efficiency of 226 Wh/km. It requires very large 106kWh battery packs that will ultimately increase their environmental impact and potentially divert scare battery materials from more efficient, but less profitable, alternatives.
As charging infrastructure improves, and improved battery designs allow for shorter recharge times, it is possible that consumers' range anxiety will decrease. This could ideally result in greater sales of vehicles with smaller battery packs reducing pressure on stretched supply chains and reducing costs of EVs overall.
The views expressed here are those of the author and do not represent or reflect the views of RTÉ
