Lexus LS600h vs Mercedes-Benz S400 Hybrid

1.770463-730844822 — The Lexus LS600h and Mercedes-Benz S400 Hybrid go head-to-head. Image Credit: Christopher List/ANM

Mine's got six speeds and yours only five, mine is newer than yours, mine has more horsepower and inlines are cooler than Vs, my daddy can stuff more M&M's up his nostril than yours… Arguments at wheels are quite a bit more productive than whatever tasks are written on our job descriptions.

But so far, funnily enough, nobody's ever boasted about fuel economy. So as these two hybrid luxury saloons roll silently into our car park, we can't think of a better way to settle the comparison test than with another epic argument. Unfortunately, though, someone ate all our M&Ms while we weren't looking and left only the brown ones. We hate those. So Amit is making us do some actual work. We quickly figure out how to have an argument anyway, only a practical one this time.

The stakes are set. We're having ourselves a cross-town race, and the loser has to shell out Dh100 for every 0.1-litre of petrol they consume more than the winner.

It's going to be epic. It's going to be the slowest race ever.

Ready set go. Go, I said go!

Basically we're driving around and the finish line is going to be Green Community, which we picked on the basis that it's the most environmentally friendly sounding place in Dubai because it has the word ‘green' in it.

DJ: I'm in the Lexus LS600h, with a huge all-aluminium 5.0-litre V8 and 438 horsepower. Immediately I start taunting Imran about his S400 Hybrid and its paltry 299bhp. "Ha ha, loser!" He then calmly reminds me that this is an economy race. Right, sorry, this is still new to all of us…

IM: I reckon I have a decent chance of winning this race because I plan to keep on Dejan's coat-tails all the way and then slam it in neutral for the last few kilometres and let the S400 roll to the slowest finish in racing history.

Right, balaclavas on, Pilotis, gloves, fresh coffees in the cupholders, zeroed odometers and we're good to go. What ensues is the most pathetic standing start ever. We're basically racing to see who can pull off slower. In fact we're not even accelerating, we're both on our brakes. The cars have now come to a dead stop…

OK, this won't work; we'll just be irritating every other road user in Dubai if we drive like this all the way to the finish line. So we're making a pit stop approximately three inches after rolling off the line. Since we didn't think this through at all, as usual, we need to add more rules to the game.

Stick to the speed limit or within 10kph below it.
Never, ever switch the engine off.

IM: Actually that immediately disqualifies me and my Merc. It has a stop-start system and it's already switched itself off.

So we waive that one, but you still can't actually turn back the ignition key. At this point we realise these cars don't even have ignition keys, so once again update the rule book with:

No touching of the stop-start buttons.
No being clever and exploiting loopholes.

DJ: That last one's mine, and should put a stop to any gaping loopholes we've obviously left open. But really it's just so I can argue with Imran about any strategic manoeuvres he might come up with. I'm already planning truck drafting, and I know Imran is a hypermiling noob since he drives a '91 Pontiac which is so dirty, it has its own ozone layer hole following it around everywhere.

IM: I don't know what Dejan means. I thought environmental friendliness was bubble-wrapping your old car battery before you toss it on the street, isn't it?

Right, now we're pretty confident we have a professional rulebook on our hands, but we'll just add that the ACs have to be running the whole time on a set automatic temperature of 22 degrees, because that's what you do in this region and this is meant to be a real-world test, plus the route won't be a crawl around Deira where the Merc's stop-start would give it an advantage, but rather a 60km lap that entails 70kph roads, back streets, traffic and open highway… As well as, of course, Dubai's natural hazards such as tyre carcasses, suicidal pedestrians, delivery motorcyclists from hell, sand storms, marauding camels, tsunamis, you just never know what can go wrong in a pioneering race like this… The Targa Dubai, as we like to call it.

DJ: So by now, the Lexus is consuming close to 30 litres/100km, and the Merc's still asleep; not a good start for me. I'm eager to get going under electric power alone, so I can catch up, while staying behind, if you're still with me…

The green flag goes down again, seriously this time, and the scores of bemused but fervent spectators (Amit and Sony) wave the brave racers off into the unknown.

Of course we have our routes programmed in the sat-navs so it's not entirely an unknown, but still.

Flag-off

DJ: My Lexus is a bit long in the tooth. It's also quite literally long; the hybrid rides on the stretched 3,091mm wheelbase. The LS has been around in only a marginally evolving shape since 1989, so it definitely looks a bit dated, but there's nothing last-century about its powertrain. Lexus's smooth V8 has been enlarged to 5.0-litres here, pushing 389bhp at 6,400rpm. Which means I haven't got a chance of tasting half of those ponies, since my tachometer is getting cobwebs at the 2,000rpm mark. I plan to stay well in the EV range, and even when I'm out of juice from the two electric motors, I'm working the petrol engine just enough to avoid inducing road rage from other motorists. But the stats are rather nice, even though this race will never call for the LS600h's full 438 total system horsepower. The batteries sit in the back below the pair of rear captain's chairs, which recline like airline seats and give you massages. They're arranged in 240 cells divided into 20 modules (the batteries, not the captain's chairs) and total power output is 49bhp. Once you start the car, you'll immediately try to start it again. The Lexus runs so eerily silent, you don't even know it's on.

IM: My Merc has way more badge prestige and if that isn't enough to declare me the winner, the S400 is the first mass-produced car with a 32-cell, 120 volt lithium-ion battery. I should feel honoured then, but, give me a good old-fashioned combustion engine any day of the week. The freshened-up grille, LED lights and new exhaust tips give the S400 a sporty look and it's powered by a 3.5-litre V6 mated to a slick seven-speed automatic which combined with the 20bhp electric motor gives mejust one horse short of 300. The S is dripping with technology and I've already got my favourite: a Pre-Safe Brake assist. With one eye on the dash to see how much juice I'm using to win this thing, there'sa high chance I could crash. But, the system detects an impending collision and gives you a warning and 0.6 seconds before disaster, it slams on the brakes if you freeze like the proverbial deer caught in the headlights.

Hitting Satwa

DJ: We're on our way, heading towardsAl Wasl Road and the crawl around Satwa. Immediately I take the lead, despite following Imran's Merc, if you catch my drift. We're going slowly enough to communicate by casually speaking out the windows, so Imran tells me he's already above the tens. The Merc's stop-start is great, but unfortunately it doesn't help when traffic keeps crawling. I'm in the 9.0-litre range as I made sure to load up the battery by running the engine well before the race. I've got brains, me. Imran didn't even bother to check if he had enough fuel, and he'll need plenty of that if I have my way in this race.

IM: The thing about the Merc is that it has a fantastic adaptive cruise control system, so I can let the car work it all out. Even in a jam, I can rest my feet on the leather dash, letting the car brake, accelerate and maintain speed (if you can call 10kph speed) all by itself. I figure the car's electronics surely know the best way to conserve fuel, better than a petrolhead's right foot which through decades of evolution has learned only to bury itself.

Unfortunately for the Merc, the cruise control is too abrupt for economy runs. It jerks forwards for the tiniest of gaps, and scrubs off speed too much, which of course means you then need more power to get back to speed. Hypermiling 101.

DJ: In the Lexus, I'm balancing between EV and petrol power constantly, my eyes glued to the instruments, so much so that I nearly rear-end a van with a vicious looking tow bar poking out its bumper. That definitely wouldn't buff out…

I can get a couple of klicks in zero-emissions mode no problem, but the slightest exaggeration in throttle input wakes up the big V8, and that's a big no-no. By the time we enter Satwa, I've got the black art fairly mastered. However, there are limits, because sooner or later the petrol engine will come on tap to juice up the electric generators. It's unavoidable, and this, together with the heavy all-wheel drive CVT, is my Achilles heel. The Merc's Achilles heel is, basically, Imran.

So far the whole way down the ‘start straight' of our race, Imran's been moaning out his window about his ever-climbing fuel usage. His six-cylinder petrol engine is good for 279bhp and combined with the electric motor he has 299bhp at his disposal. Sounds alright, but remember that he has to exercise finesse with over two tonnes of metal, rubber, glass and lithium-ion. In any case, he should be using less than 11 litres of 98 Octane per 100km, especially with his regenerative brake system and stop-start. Too bad he's riding on massive AMG rims with performance rubber, because the low-rolling resistance tyres this car should come with would no doubt aid Imran's green cause.

And he takes the inside line!

DJ: I'm learning to love the traffic, and hope this carries on all the way to Green Community… My mileage is getting better and better the more I get used to balancing EV and petrol. At one point I dip into the sevens and stay there halfway down Jumeirah Beach Road. But how will my two-and-a-half tonnes of Japanese high-tech lard get up to speed on the highway? We're about to find out… Uh-oh.

Immediately the economy starts getting worse as I hit the 80kph speed limit on Umm Suqeim.

IM: I've never had a bigger grin than I'm currently wearing. My cruise control is finally doing something right and I am seeing 10 litres/100km for the first time since the green flag. Dejan calls to tell me he's getting 11… I hope he remembered to bring some ‘loser' money…

DJ: But then, just after we pass Mall of the Emirates on our right, I look in the mirrors and I can't see Imran. I'm pretty sure he's run out of fuel in that barge of his. Anyway, rules say we have to stick together so I pull over and whip out my lithium-ion. I mean my Nokia.

DJ: "Where are you?"

IM: "I've already won, ha-ha, I'm in the Greens."

DJ: "Oh OK, well done, except the finishing line is Green Community." For crying out loud, and because I don't want to cheat (actually I would, but the photographer is riding shotgun and he'd tell) I have to sit on the side of the roadwith the engine running, and I have nostop-start, arrgh!

The final straight

IM: I had to rush my Merc and so I've ruined the economy, which means Dejan is back in the lead… Five minutes later and we hit the highway proper.

DJ: Unbelievably, I manage to settle the Lexus into a nice aerodynamic rhythm and I'm averaging a steady 10 litres/100km. I've no idea how Imran's doing but my lithium-ion suddenly rings and he tells me that the Merc is terrible at speed. About 13 litres!

Finish line

DJ: We made it. There's been no marauding camels or tsunamis, but I did almost have an accident and Imran got lost, although that happens on every photoshoot anyway, even if we do it in the Gulf News studio, which is a square room with nothing in it. The slow cruise through Green Community lowered our fuel usage one last time, and at the 57.7km mark, I'm victorious with an average of 10.6-litres per 100km. Amazing for an all-wheel drive Lexus weighing two-and-a-half tonnes and powered by a 5.0-litre V8. Even stop-start and regenerative braking couldn't help the little six-pot Merc do any better than 11.7-litres per 100km; although it did do a few extra kilometres. The world's slowest race took us through a 60km loop of New Dubai and a Lexus LS600h won it by a hair's breadth.

IM: We think there's a valuable lesson here, and that lesson is: put foot while the fuel's still cheap. And when the petrol prices rise again, just buy yourself a Dh472K Lexus LS600h L.