GREEN-LIVING S550E LACKS SPARK
Mercedes’ plug-in luxury sedan doesn’t quite live up to its electric ambitions
The purpose of any automobile road test is to give you, the reader, an expert opinion on a vehicle you might choose to purchase. The essential ingredient to this evaluation is not only how it performs in absolute terms but, just as important, how it fares against other vehicles.
Of course, it has to be a fair comparison. Comparing a Caravan to a Corvette, for instance, is just silly. And expecting a Hyundai to compare with a MercedesBenz is just delusion masquerading as optimism. Or is it?
Rather than leave that cliffhanging, I’ll let the cat out of the bag and give you my conclusion as an introduction: The most interesting part of evaluating Mercedes’ new S550e plug-in (a hybrid mating a 3.0-litre turbocharged V-6 to an 85-kilowatt electric motor) is that it compares very favourably to Benz’s conventional S550 (powered by a traditional gas-fuelled V-8, twice turbocharged), but it gets its ass kicked, at least in terms of its “hybrid” performance, by a lowly Hyundai Sonata Blue Drive. Let me explain. The attraction of the S550e is that it promises virtually all the power of the V-8 S550, but with hybrid-inspired frugality.
A spec sheet comparison bears this out. The S550e boasts 436 horsepower, the V-8-powered S550 but 13 more. And judging by Transport Canada figures, the fuel economy battle is a smackdown: The S550e is rated at 11.1 L/100 km in the city and 8.1 on the highway and the conventional S550 numbers are 14.8 and 9.8. Transport Canada estimates that the typical S550 driver will save about $1,500 a year in fuel if they opt for the hybrid version.
The real world bears most of this out. The performance difference is more than the minuscule difference in power ratings would suggest; the S550e, thanks to its 8.7 kilowatt hour lithium-ion battery, weighs 70 kilograms more. But the hybrid version is more than peppy enough. There is even something of a feline growl from its twice-turbo’ed V-6.
The S550e is also significantly more frugal than the V-8. Part of that is the claimed 32 km of electric-only range. Part of it is because the motor only has six pistons instead of eight. And part of it is because the traditional S550 really sucks back the high test. Transport Canada may rate the V-8 at 14.7 L/100 km in the city, but I seldom saw less than 20 L/100 km, the highest number the digital readout would display. By comparison, the approximately 12 L/100 km I averaged in the city with the hybrid was positively exemplary.
So game over, right? Markedly better fuel economy, almost equal performance and surprisingly engaging comportment would seem to indicate the S550e a winner. Especially since Mercedes-Benz Canada is being very strategic with its hybrid pricing. The S550e’s $117,300 base MSRP is $2,200 less than the S550. Except … I can’t help thinking that Hyundai has a better handle on hybridization than Mercedes does. The S550e does not fare well in any comparison of electrical powertrain with an electrified Sonata, which is barely a third of its price.
First of all, Hyundai imbues the Sonata with a bigger battery — 9.8 kWh versus the Merc’s 8.7 — to power its electric motor. This does two things, one has to do with speed and the other, distance.
The Blue Drive Sonata can cruise at much higher speeds solely on electric power than the Mercedes. The Hyundai impresses, easily achieving 140 km/h with decent acceleration on electric power alone. Though Mercedes claims the same for the S550e, in reality its EV limit is more like 125 km/h.
The Blue Drive Sonata claims more electric-only range as well: 41 km for the Sonata versus 32 for the S550e. Part of this discrepancy is explained by the difference in size. The S550e is a full-boat luxury sedan, while the Sonata is a relatively puny family four-door. One weighs in at a heavyweight 2,215 kg, the other at a middleweight 1,655 kg.
What that weight discrepancy does not explain, however, is this: The Hyundai always delivered the promised 40 or so kilometres of electric-only range. The Merc, on the other hand, never went more than 18 kilometres on battery power alone. It was usually less — 16 km was typical. The general rule with the S550e was that whatever the digital display was boasting as range needed to be divided in half.
This couldn’t be explained as different weather conditions. If anything, the Hyundai suffered through a colder patch of our winter weather. Nor did city or highway use make much difference to the Hyundai’s advantage. The Sonata’s range was almost the same on highway (usually a greater draw on batteries) as city; the Merc, by comparison, eked out fewer electric-only kilometres at speed.
Nor was the Hyundai babied in comparison. In fact, the opposite was true. Since it cruised so easily at speed, we hustled around in the electrified Sonata. The Merc, on the other hand, needed to be treated like the proverbial baby if we wanted to “sail” electrically.
What does all this mean? I am not quite sure. How much of this is an unfair comparison? How much is a result of the significant weight difference? Again, I can’t really be sure.
This much I do know. Mercedes touts itself as a technological leader in the automotive forum. I expect a Mercedes-Benz product to outperform a supposedly lowly Hyundai, even accounting for disadvantages of girth and avoirdupois. At the very least, I expect that promises of electric range made on the dashboard should be proven on the road.
So getting back to the original treatise of any road test, yes, I would definitely choose the S550e over the conventional S550 in a heartbeat. Over the Hyundai Sonata Blue Drive? I’m not so sure.