Buy a plug-in hybrid and never plug it in, and congratulations: You’ve invented the world’s most complicated way to waste fuel. There’s really no point in buying one if you don’t charge it, and this is a bigger issue than you may think.
You’re not going to come close to the manufacturer’s claimed efficiency numbers. It might even use more fuel than the same vehicle with the same engine but without electrification. It’s just not a great idea. That is, unless you’re talking about the Mercedes-Benz GLE 350 de, which I tested not too long ago.
This diesel-electric mutant shouldn’t be good, but I liked it for a few reasons—including its ability to sip fuel rather than slurping it.
A PHEV For The Lazy Charger
Photo by: Andrei Nedelea
The GLE 350 de is a true unicorn with its diesel plug-in hybrid powertrain. Diesel engines in general are now endangered in Europe, and plug-in hybrid diesels barely exist at all.
Making a diesel PHEV is hard, which may be why only Mercedes makes them today, as variants of the C-Class, E-Class, GLC and GLE. The diesel engine needs heat to work at its most efficient, likes long slogs at constant rpm and is just not as well suited to the stop-start life of a PHEV. In a diesel, there’s also a particulate filter that really doesn’t like it if you turn off the engine midway through its regeneration cycle.
And yet, somehow the GLE 350 de works like charm. It has a special party trick too: It doesn’t turn into a gas guzzler when juice from the battery runs low. I put it through an electric range test, and it managed to complete just under 53 miles (85 km) without trying to hypermile before it started up the combustion engine.
Mercedes says it can do over 62 miles (100 km) on one charge on the WLTP test cycle, but I still came pretty close to matching that without trying to drive it economically. I then charged the car to about 50% and drove it around in hybrid mode until it again ran low, after which I drove it almost exclusively in Sport mode until I returned it to Mercedes.
I reset the average consumption after doing the EV range test, and by the time I returned the car, it was showing 8.1 l/100 km, or 29 mpg. For a two-liter four-cylinder diesel, it’s not amazing, but for a near-6,000-pound German fortress on wheels that is also constantly putting juice back into its big 31.2-kWh battery, it’s actually alright. You could probably get it even lower with a lighter right foot.
Mercedes says you can expect 0.9 l/100 km (470 mpg), which is absolutely possible if you always have the battery topped up. However, even if you don’t charge it, the GLE350de won’t ruin your wallet with its fuel consumption, and you don’t have to live uphill from everything to get decent efficiency numbers.
Electric Enough For Your Commute
Photo by: Andrei Nedelea
You should still charge up as often as you can, though. The electric-only mode gives enough performance for daily use and merging onto the highway. It will even do 86 mph (140 km/h) without waking the diesel, meaning you can commute solely on electrons.
When the four-cylinder turbodiesel does start up, you know it and are instantly aware of how many cylinders it has and what fuel it burns. However, it doesn’t ruin the GLE’s excellent overall refinement, and it actually sounds vaguely sporty under load as revs build.
Charges Like An EV
Photo by: Andrei Nedelea
The vast majority of plug-in hybrids can only AC-charge at up to 22 kilowatts. But like any current Mercedes PHEV, this GLE can DC fast-charge at up to 60 kW. That’s faster than some pure electric city cars.
Juicing the GLE 350 de up from 10% to 80% takes just 20 minutes, which is excellent for a PHEV and makes charging it more convenient. Knowing that you don’t have to wait around for hours for it to charge, as with most PHEVs, may also encourage owners to use public chargers more often and thus drive more electric miles.
Quick Enough
Photo by: Andrei Nedelea
Performance-wise, the GLE 350 de was less brisk than I expected, given its 333 hp and 553 lb-ft of torque. It never feels fast. It actually felt a bit slower than the 6.9 seconds Mercedes claims for the 0-62 mph (100 km/h) sprint. In-gear acceleration was about on par with a larger-displacement six-cylinder diesel, although it couldn’t keep up with a GLE 450 d, which has a bit more horsepower and the same peak torque yet somehow feels considerably quicker.
Having owned several diesels myself, I am a bit partial to the old oil burner, and this one didn’t disappoint. It’s torquey and cheaper to run, and it makes you feel better about owning a 5,800-pound luxury SUV. It’s even better in the smaller and lighter C-Class and GLC, which are both more fun to drive and more efficient. It’s not hard to see why I saw so many of these new Mercedes diesel PHEVs in Stuttgart and even parked in and around the automaker’s Sindelfingen factory.
Overengineering (Sometimes) Works
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Source: Andrei Nedelea
Driving a GLE 350 de, it kind of feels like you’ve found a cheat code. Its existence is improbable, and if you look at its parts separately, it sounds like it’s not going to work. Mercedes somehow made something like this not only work, but work well and more than justify its existence.
There is a price to pay for all this unexpected brilliance, though. It starts at just under €90,000 ($105,000) and, with only a few of the available option boxes ticked, my tester cost over €100,000 ($116,500). That is a lot, but you are getting a lot of plug-in hybrid for the money, with oodles of space, style and comfort. And there’s another perk: There’s nothing else quite like it.
