The Mercedes GLC 300e has one of the best electric ranges among plug-in hybrids. Would he enter the world of electric cars?
We are not going to rekindle the debate, and we all know that plug-in hybrid cars have a very special position. Like all contemporary ultra-versatile products, they are not really good in terms of electrical efficiency, while fuel consumption can be much higher than with a purely thermal gasoline equivalent if the battery is empty. On this last point, however, this is not always true. In any case, we can also see things differently, again, with vehicles that offer the best of both worlds: the engine can operate in hybrid mode on long journeys, while the generous batteries make it possible to carry out the daily trips at a lower cost for the wallet and for the planet.
Actual consumption of plug-in hybrids: the results of our measurements
Always shunned because they are rarely used well, plug-in hybrid cars have therefore benefited from the latest developments in electrical technologies to improve their performance: electronic management reserves a more comfortable margin to no longer cause consumption to explode when the battery is empty, ranges are becoming more and more important, and other new equipment is appearing. Proof of this is, for example, with the latest generation of Toyota Prius, which is even equipped with a heat pump. Or even with the new version of the Mercedes GLC 300e, which goes all out in this area.
A technical sheet that we should never have read
Completely renewed, even if it is not visible at first glance, the Mercedes GLC pushes the potentiometers to a new level. If the thermal part does not bring anything new, the electric traction chain is close to the world of electrics: the battery with 31.2 kWh gross capacity and the 60 kW fast charging device have nothing to envy of modest electric city cars! This gave rise to a strange existential question within the editorial staff: can the best plug-in hybrid cross the country on the highway without burning a drop of gasoline as well as a purely electric city car?
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Because if the bet was lost in advance just a few years ago, today’s technologies and ecosystem allow, on paper at least, this kind of madness as crazy as it is useless. And for good reason: even with astonishing autonomy, it will always be preferable to use hybrid mode in this context. What plug-in hybrids are made for. But it highlights the progress of electrical technologies and the rapid development of the motorway charging network.
To tell the truth, we started this journey without any real fear of failure. Previously scrutinized as part of the Supertest (to be found soon in detail in our columns), the Mercedes GLC 300e was very surprising. On the one hand, its performance in terms of fast charging is surprising. Once connected to a unit capable of delivering the right power, the battery can be fully charged (0-100%) in just 31 minutes! On the other hand, the total autonomy is a real surprise since it can be incredibly homogeneous in Electric mode whatever the terrain.
This is what we quickly discovered on the first stage of our 500 km motorway journey: while we had timidly planned a first refueling around sixty kilometers from our starting line, the GLC 300e was able to ensure a stage of 103 km before being recharged! A behavior which therefore modified all our prior projections, pushing us to adapt. A lesser evil, as the density of the network allows you to play with the load base to best optimize journeys and refueling. And this without a journey planner since the GLC was not designed for this type of exercise, to say the least absurd.
Travel time for 500 km: 7h14
Traveling in electric mode with a plug-in hybrid vehicle is in no way different from traveling in 100% electric mode, so let’s go straight to the results. Even if it meant playing the game, we chose to drive at the speed limits, as with all the cars that pass through our hands on this road. Especially since, let’s take this opportunity to clarify, the small difference in consumption between 110 and 130 km/h would not have made it possible to go really faster. In the end, we recorded a total of 4 hours 20 minutes of driving over these 500 km, or an overall average speed of 115 km/h. Note that the Mercedes GLC 300e’s counter continues to run even when the vehicle is stationary, for a total of 19 minutes here. That’s a little more than two minutes per stop (time to reach the terminal in the middle of the areas). However, as always, we will apply a flat rate of four minutes per break in addition to the driving time, to take into account the handling required by the terminals.
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Which brings us to the most interesting part: for this trip, we had to refuel seven times at the fast charging stations. That’s a lot, but let’s not forget the GLC 300e’s ability to refuel very quickly. In addition, it should be noted here that despite the repeated demands and the significant rise in battery temperature during recharging, performance did not deteriorate over refuelings. In the end, we remained immobilized for exactly 2 hours and 26 minutes. In detail, during the first and last recharges, where the terrain was not too demanding, we never exceeded 25 minutes of recharge. In the Morvan, where the autonomy did not allow us to skip areas, we did not exceed 15 minutes in order to optimize recharges.
In short, in the end, adding up the driving time, the charging times and the fixed price for each stop, this 500 km journey using the sole power of the electric motor on board the GLC represented a total of 7 hours 14 minutes. This allows it to easily beat the Renault Twingo e-Tech, which has almost the same autonomy in these conditions. In terms of charging time alone, the GLC 300e took just 15 minutes longer than a Zoé R135, which however only stopped three times on this journey.
In terms of consumption, the German SUV presented an average of 27.7 kWh/100 km. Depending on the actually usable capacity of the battery, estimated by us at nearly 24.8 kWh, the GLC 300e therefore has an average range on the highway of 89 km. Unsurprisingly, consumption is explosive. According to our database, only the Aiways U5 and Volkswagen ID. Buzz posted such a high average on this course. The BMW iX xDrive50 and Ford Mustang Mach-E AWD increased to 26.5 and 26.0 kWh/100 km respectively.
The only necessary recharges, allowing us to cross the finish line with a minimum of 20%, represented a total of €76.6, or a cost price of €15.32/100 km. Depending on the terminal used at the end of the journey to find the starting capital, this would bring the cost from €16.28/100 km (AC charging at home) to €17.67/100 km (DC charging). Considering our preliminary measurements on the highway in hybrid mode with the battery empty, and based on an average price of SP95-E10 at €1.971/l at the time of writing, the Mercedes GLC 300e would have presented a cost of final cost of €16.95/100 km.
Too much is like not enough
Traveling solely on the power of the electric motor in a plug-in hybrid car has absolutely no interest. And this even with one of the models with the best autonomy on the highway. This exercise, on the other hand, allows us to highlight the fairly sustained development of the motorway charging network, which even allows vehicles that were not designed for that (but still equipped with powerful rapid charging) to cross France. In other words: autonomy, since it must be remembered again, is absolutely no longer a problem.
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But it also shows that the Mercedes GLC 300e is tickling the electric world, and that it can do as well as the most modest electric city cars in the most demanding of exercises. A feat which seriously questions the usefulness of such a large battery in a vehicle of this type. Because in addition to the electric ranges which go well beyond the daily needs of the vast majority of drivers, the technical choices do not serve efficiency: the weight, formidable in the city, and the transmission, which consumes energy all the time, consume the GLC like no other electric vehicle on our mixed route. The cost of use, with the same charging method, will therefore be higher than with an electric vehicle.
On the highway in hybrid mode, the cost price could be equivalent to that of an electric vehicle which would consume, according to our basis, around 26 kWh/100 km. The equivalent of an electric SUV from the upper segment, larger, more spacious and efficient than the GLC 300e. All that remains for this plug-in hybrid is the possibility of freeing itself from recharging on the highway, assuming that its driver does not take any breaks over the nearly 570 km of autonomy allowed by its fuel tank. Otherwise, it will go as fast as a BMW iX or a Kia EV6.
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