2023-07-17 13:01:09
Why would a heavier electric car consume less electricity than a lighter electric car? The answer isn’t obvious, but a YouTuber took apart a Tesla Model S Plaid to drastically reduce its weight and increase its performance. But not everything went as planned.
The weight of (electric) cars is often singled out. In question, energy consumption (whether gasoline or electricity) which increases with the weight of the vehicle. It is for this reason in particular that France and other countries have adopted a weight penalty. And we must not forget that the weight of a car also increases the amount of materials needed to produce it. This then mechanically increases pollution during the production phase.
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More is weight really a problem for cars, and in particular electric cars? Can we consider other ways to reduce the energy consumption of an electric car? Well precisely, a Youtubeur made a surprising experience to say the least, which brings a little water to the mill of our problem.
A Tesla that loses 300 kg, what does it give?
On the YouTube channel BoostedBoiz, the youtubeur has made a totally improbable video. He completely dismantled a 1,020 hp Tesla Model S Plaid, to lighten it as much as possible. He thus removed the hood, the trunk, the doors, the windows, the seats, and a whole bunch of furniture and accessories not necessary to drive it. This made it possible to pass the weight of the electric sedan from 2,100 kg to only 1,800 kg on the scale.
Its objective: to reduce as much as possible the time necessary to achieve an acceleration from 0 to 60 mph (about 96 km/h). Originally, the American car only claims 2.2 seconds on this exercise. The youtuber measured 2.35 seconds with his own original electric car. And in the 1.8 tonne version… the measurement is 2.43 seconds. But the man clarifies in the comments that he managed to go down to 2.31 seconds a few hours after posting his video.
This experiment, however, allows us to draw some conclusions, and not only on the performance of a light or heavy car. The first conclusion is clear and shared for many years in motorsport: yes, a lighter car is more efficient. But does it really consume less energy?
The consumption of a car in relation to its weight
This second question is more delicate. In the first place, one would be tempted to answer in the affirmative: a lighter car (electric or not) necessarily consumes less energy than a heavier car. But we must not forget an essential element: aerodynamics.
During his first tests with the “naked” car, the youtuber performed less well than with the heavier car. Observers then saw an obvious reason for this: air resistance had increased because of the absence of windows, trunk and hood. The second test which makes it possible to do better than the car with its original weight thus strikes a blow to this explanation.
But as we recalled in our file on the aerodynamic drag coefficient (Cx) of a car, the consumption of a vehicle at high speeds is mainly linked to its aerodynamics. Conversely, at low speeds, a car’s consumption is more related to its weight.
Light car or aerodynamic car?
In other words, a light car reduces fuel consumption in the city (but also pollution during its production phase), whilean aerodynamic car reducing fuel consumption on expressways. Want the best of both worlds? It is a light and aerodynamic car, which ticks off both of these advantages.
But be careful, because a light car, with unfavorable aerodynamics, can consume more energy at high speeds than a very aerodynamic heavy car. Why create a penalty (or bonus) linked to weight… and aerodynamics?
We can take the example of the Volkswagen ID. Buzz and Mercedes EQS. The German sedan is almost the same weight (2.5 tonnes) as the electric van (2.5 tonnes) to within a few kilos, but their consumption has nothing to do.
The Mercedes announces a theoretical consumption of 17.2 kWh / 100 km on the WLTP mixed cycle against 20.8 kWh / 100 km for the Volkswagen van. With a Cx of 0.2 for the first against 0.285 for the second. Proof here that aerodynamics is very important on consumption.
Future lighter electric cars?
The good news is that manufacturers want to reduce the weight of cars, while improving their aerodynamics. We can cite the boss of Renault, who wants small batteries with light and compact cars like the electric R5, or even Ford, who wants to design his SUVs like a TGV, with an aerodynamic shape and a contained weight.
The objective of manufacturers is to reduce energy consumption in order to be able to install smaller batteries in their electric cars. With, as a consequence, a drop in the cost of production, and therefore a drop in prices for the consumer, or an increase in margins for investors.
Moreover, in a recent study, Transport & Environment announces that ” the reduction in battery size enabled by the manufacture of smaller electric vehicles is the most effective way to reduce the demand for metals (-19 to -23%)“. And to go further, the NGO ” calls for policies to encourage the production and release of affordable entry-level small electric vehicles, to adopt innovative battery chemistries and to limit solo trips. These measures would reduce demand for key metals (lithium, nickel, cobalt and manganese) by 36-49%« .
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