Comparison Review: Mercedes S400 Hybrid Vs. Lexus LS600h L

Luxury means many things to many people, but nobody doubts luxury cars should be crammed full of the latest technology… and what says “technology” in today’s car market quite like “Hybrid”? In a strange inversion of history, Lexus created the world’s first hybrid luxury flagship from a vehicle that was clearly inspired by the Mercedes S-Class, and now Mercedes is fighting back with its first hybrid sedan, the S400 Hybrid. So, is Lexus’s hybrid head-start enough to fend off a challenge from the vehicle that inspired its birth over a twenty years ago? The only way to find out is in TTAC’s most expensive comparison test ever.

Despite catering to a similar crowd, the Lexus and Mercedes hybrids could not have more different missions in mind if they tried. Lexus’ fantastically complicated AWD hybrid system was designed with V12 performance in mind. Mercedes on the other hand decided to take the simplest route to hybridization possible by inserting a smallish electric motor between the engine and transmission. Either way you slice it, if you are shopping for a car to be driven in and still somehow care about the baby seals, these two cars will provide the best fuel economy in the luxo-barge market (which isn’t saying much). Let’s dig in.

The LS 600h L is best known for being the most expensive hybrid vehicle on the market, a fact that earns it endless county-club bragging rights, but demands that we talk price upfront. Starting with a base price of $111,350, our press car was fitted with the $10,835 optional “Package C” which included everything except the radar cruise control and delivered a total MSRP of $123,060 after the destination charge. For the fully-loaded buyer, the $12,335 “Package D” will ring the total up to $124,560.

While nearly 125-large may sound like a deal breaker for even the wealthy, the LS 600h L’s German competition starts at $91,000 in the form of the Mercedes S400 Hybrid. Comparably equipped, the S400 Hybrid ends up at an eye-bulging $116,275. And if option-ticking is your thing; $123,852 buys you a fully-loaded German hybrid. Of course if you have a driver, the cost of the vehicle is likely to be unimportant, but I am told by the wealthier set that a “discreet” ride is usually preferred to a Maybach or Rolls. Noblesse oblige. MSRP winner: LS 600h L.

When the LS 600h L arrived and I peered out my window, I was impressed by the fact that the styling didn’t impress. It’s not that the LS is boring, it’s just that the Camry shares many of the same lines. Taken by itself, the LS is a handsome vehicle, and parked next to a Camry you can see the LS is much, much larger, bolder, and has greater attention to detail. When separated, however, the resemblance comes to mind more easily. Oddly enough, Lexus decided not to use their mid-cycle refresh for the 2010 model year to differentiate the LS from the Toyota models, instead the LS received a three-bar grille that looks more Avalon than Lexus to me. In contrast, the S400 Hybrid may share some styling cues with the C300, but the overall Mercedes design is far less subtle than the Lexus. While I still long for the style of the W140 S-Class, there’s no mistaking the S-Class is the biggest Benz available on our shores. Exterior style winner: S400 Hybrid.

Lexus’ skills at cabin crafting are obvious inside the LS. The range topping Lexus gets full leather upholstery, complete with a single-needle stitched dash and door panels. While the shapes may be the same as the LS 600h L’s lesser cousin (the LS 460), the LS 600h L will make you feel a touch more special. Owners of the 460 appreciate the fact that a base LS delivers a world-class interior for 60-large, LS 600h L buyers may find the nearly identical interior a turn off. If you are spending the cost of a Midwest family home on a car, you probably expect something unique.

The S400 Hybrid has the odd benefit of being the cheapest S-Class in the USA. (Mercedes decided not to sell the short-wheelbase S350 here which would compete directly with the LS 460 in the 60K+ segment.) This brand positioning means that there is no $60,000 car on American roads with identical styling to your high-rolling-hybrid. Despite the fact that the LS 600h L delivers an interior put together with more sumptuous feel and precision than the Germans could hope for, the uniqueness factor pushes the S400 to the top on our interior scale. Interior style winner: S400 Hybrid.

As a base model, the S400 doesn’t have to promise range-topping performance, which is good since this hybrid Benz receives an Atkinson-cycle version of Mercedes’ ubiquitous 3.5L V6. Typically Atkinson-cycle engines are down on power compared to their Otto-cycle versions, but interestingly Mercedes has fitted a new cylinder head, different pistons and a modified camshaft which actually increase the power over the version used in the other Merc models. In addition a 20HP, 118lb-ft electric motor is added, bringing the system total power to 295HP and 284lb-ft, topping the 268HP and 258lb-ft rating of the C350. While the S400 Hybrid delivers more power than the V8 S430 (circa 2006) and accelerates to 60 a tenth of a second faster (7.2 to 60 as tested), in this decade a luxury car with a 0-60 in the 7 second range is fairly slow.

Lexus has long embraced technology, but only recently come to admire performance. To this end the LS 600h L is equipped with a slightly de-tuned 5.0L V8 engine from IS-F (instead of the 4.6L from the LS460.) In LS duty, the large V8 makes 389HP at a lofty 6400RPM and 383lb-ft of twist at 4,000RPM. Since these numbers are not terribly exciting in their own right, Lexus added a pair of electric motors good for 221HP and 221lb-ft. Due to the way the hybrid synergy drive system works (tech nerds can find a wealth of information here), you don’t exactly add up 389HP and 221HP from the motors and get 610HP; rather, the system horsepower ends up at a conservative 438HP.

Lexus is fairly cagey on the combined torque output of the LS’s hybrid system, but I estimate it to be at least 400lb-ft and covering a very broad RPM range, thanks to the electric motors. When the engine is shut off at a stoplight (saving baby seals), a quick romp on the go pedal summons 60MPH in 5.4 seconds (TTAC tested), which matches the 5.4 second time Lexus quotes for the LS 460 L. What this number doesn’t indicate is the shockingly linear fashion with which the LS delivers this thrust: no shifts, no gaps, no acceleration swells, just constant press-you-back-in-your-seat thrust until you decide to lift. Lexus says the top speed of the LS hybrid is 160MPH. I believe it. Performance winner: LS 600h L.

When the going gets twisty, it’s frankly not important that a large luxury sedan handle well. What is important is that it gets the job done with no fuss, minimal squeals and no unnerving rear end motions. Since both sedans are equipped with load-leveling air suspension setups, I expected a fairly similar ride, and in practice both the S400 and LS 600h L lived up to my expectations. Both deliver extremely compliant rides on a variety of pavement, gravel and dirt roads. Both vehicles offer a “Sport” mode but only the Lexus seemed to actually deliver the hoped-for change to suspension behavior with Sport Mode activated. If you ever give Jeeves the day off, a this cetaceous mannerism-taming mode is a clear “must have.” While I would never call the LS 600h L a “corner carver,” grip is fairly impressive, and the AWD system provides an extremely well balanced feel, while the massive Brembo brakes stop the 5,360lb sedan without drama every time. In contrast, the S400’s personality doesn’t invite any hurried shenanigans, which is good because it just can’t muster the hustle of the Japanese competition. Handling winner: LS 600h L.

No luxury vehicle would be able to show its face at the country club without the latest in whiz-bang gadgets. Trouble is, both the S-Class and LS lines are getting old and luxury shoppers may be surprised to find that a new Ford may provide snazzier gimmicks than either luxury sedan. Both the LS 600h L and the S400 have USB music device integration, navigation, big LCD screens, Bluetooth hands-free, self-closing doors, four-zone climate control and more buttons and knobs than NASA mission control, but the graphics on both nav systems fail to achieve the “wow” factor that the latest iDrive delivers.

The Mercedes brings the latest in dynamic air-seats to the fight, which will massage Jeeves’ back and inflate bolsters to keep him planted while evading the paparazzi. The Lexus, however, delivers one of the better backseat experiences in the business. Not only does the LS 600h L’s right rear seat recline like the S-Class, but it has an ottoman, a walnut tray table and a superb vibrating shiatsu massage system to boot. Unlike other systems that use air bladders to attempt to work out your knots, the Lexus system appears to uses rollers inside the seat, and can deliver a surprisingly deep massage.

When hiring a Jeeves, it’s important to remember to test parking skills in the interview. While Mercedes and Lexus both have parking aids to help the parallel-challenged, both managed only to bring new heights of frustration to the parking process for everyone involved. The Mercedes system won’t actually park for you, but it will attempt to guide you, provided the space is large enough for a greyhound bus and you follow the guide-lines on the screen with Germanic precision. Fail to follow ze commands visout qvestion and the system will give up on you. The Lexus on the other hand will parallel park or back your car into a perpendicular parking spot all-by-itself… If you give yourself a few hours to figure out which buttons to push and how to move the square into the right spot. Sadly Ford’s ultrasonic park assist in the Lincoln MKt, Ford Explorer and Focus are so easy to use and so fast, both the Lexus and Mercedes systems seem useless. Just hire a Jeeves that can park. Here the Lexus takes the lead because it can actually park itself (given enough patience). Gadget winner: LS 600h L.

The Germans have had a reputation for over-engineering things for decades; similarly the Japanese have had a reputation for engineering everything to perfection. Luxury buyers expect not only the finest in craftsmanship, but also the finest in engineering. In this category neither disappoints. While it seems superficially that Lexus has lost the technological edge over the past decade, the hybrid system in the LS 600h L will remind you who has a crazy R&D budget.

The Lexus CVT and AWD system are a true marvel, unlike a “regular” CVT, the Hybrid Synergy Drive transmission in the LS 600h L uses planetary gear sets and motors to change ratios. Although the idea is the same as the transmission in the Prius, the LS 600’s unit is far more complex, containing two power-split units and a two speed motor reduction gearbox on one of the electric motors designed to improve efficiency and reduce noise at speed. Even the gear-driven Torsen unit was specially designed for the LS’s transmission, to meet Lexus’ rigid standards for noise and physical dimensions.

By comparison, Mercedes’ hybrid system seems almost rushed. While the S400 may be the first lithium-ion hybrid on the market, the reason for the more dense battery design is that, due to a lack of space, Mercedes needed the battery to fit where the 12V battery normally goes. As you might guess this means there is no 12V battery in the S400, instead the lithium-ion battery and motor pack together replace the motor, alternator and starter. While bragging rights for being the first to carry a lithium-ion battery are nice, trying to explain how the Lexus’ transmission works to passengers delivers Lexus the lead here: Engineering winner: LS 600h L.

When selecting the perfect car to shuttle you to the board room, luxury features are by far the most important consideration. Out on the road in the LS, the first thing you will notice (while being massaged), is how quiet the cabin is. “Quiet” doesn’t do it justice, I’m talking eerily quiet. At the first push of the power button you are inclined to think “well it’s a hybrid so it’s quiet because the engine isn’t running.” In reality the engine was running, this car is just that quiet.

In contrast, the S400 delivers more wind noise at speed and a distinctly un-luxurious V6 noise from under the hood when pushed. While I would never choose a CVT over a traditional automatic for my own driving, the LS’ hybrid CVT is actually the perfect companion for executive transport (the last thing you would want is a harsh shift to spill your champers.) Speaking of that CVT, at 80MPH the engine in the LS 600h L is barely spinning faster than idle keeping engine noise at an absolute minimum. If you are late for your meeting, three digit speeds are attainable in both sedans, but again the LS retains its luxurious pose and low noise levels even at these speeds. If the LS is in your stable, don’t spare the whip. After all, it’s Jeeves’s license, not yours. Luxury winner: LS 600h L.

Last, and quite appropriately, least, we arrive at fuel economy. Anyone who derides the S400 or LS 600h L for their low economy numbers obviously missed the point. If you really cared about economy you’d buy a Prius, and if you really cared about the environment you’d have Jeeves pedal you to work in a rickshaw. Instead the luxury hybrids are about technology, status and political correctness. Even so, in mixed driving we averaged 22.3MPG in the S400 over 800 miles. The best mileage recorded was a 50 mile highway journey averaging 65MPH and 29MPG. We can, of course, thank the V6 for these numbers, as the Euro-only S350L gets similar numbers on the highway.

Does that make the S400 the winner? On paper, yes, but in practice, the LS 600h L surprised us with EPA crushing real world economy numbers. According to the government, the LS 600h L should deliver 20 MPG city and 22 Highway. On a 350 mile trip down to Los Angeles for the LA Auto Show, we averaged 23 MPG at an average speed of 77 MPH which included going over the Grapevine. I was however still prepared to write off the hybrid tech as useless until we got stuck in LA traffic, where the hybrid drive really shines. A 28-mile trip from downtown LA to Covina which took a grueling two hours resulted in a lofty 32 MPG average for the LS. If you live in New York or LA, the LS 600h L actually might be a penny-pincher in traffic. Of course, you can buy about 7,500 gallons of gasoline for difference in price of the LS 460 L and LS 600h L. Economy winner: Tie.

At the end our two week back-to-back test, it became obvious that the LS 600h L is the best pure hybrid luxury vehicle in the $100,000 price point. The isolation, the CVT and the AWD, all combine to make a vehicle that is perfect for the person to whom Luxury means floating on a cloud. The LS 600h L will never have the athleticism of the BMW 7-Series, and it may not have the brand cachet of the S-Class, but it does deliver the pinnacle in isolated transport.

Lexus and Mercedes provided the vehicles, insurance, and one tank of gas per vehicle for this review