The Porsche Panamera Turbo Sport Turismo—to hybrid or not to hybrid?

If everything had gone to plan, you'd have read our review of Porsche's mighty Panamera Turbo S E-Hybrid Sport Turismo last summer. Maybe one of the longest names of any car on sale today, it has the specs and a price tag to match. How does 680 horsepower (507kW), 626lb-ft (848Nm) and a starting price of $190,200 sound?

But things didn't go exactly according to plan. Somehow, other drivers kept driving into the back of the range-topping hybrid on Porsche's East Coast press fleet, necessitating some continued rescheduling that meant we didn't actually get any seat time in it until the last clutches of winter, hence, the snow in the pictures.

However, it wasn't all calamity. To ameliorate one cancellation, the people at Porsche sent us a non-hybrid Panamera Turbo Sport Turismo (MSRP $155,500, 550hp/410kW, 567lb-ft/768Nm) as a stand-in. That provided the opportunity to make some comparisons between the two most powerful Panameras and explore what difference 14.1kWh of lithium-ion batteries and a 134hp (100kW), 295lb-ft (400Nm) electric motor make.

Many of the technical specifications of both Turbo and Turbo S E-Hybrid are the same as the shorter-named, less powerful, less expensive Panamera 4 E-Hybrid Sport Turismo, which we reviewed last year. They're all the same length (198.8 inches/5,050mm), the same width (76.3 inches/1,938mm), the same height (56.4 inches/1,432mm) and have the same 116.1 inch (2,949mm) wheelbase. They all feature the same suspension design—double wishbones at the front wheels, multilink at the rear, with adaptive air dampers (PASM in Porsche-speak). All of them are all-wheel drive and use the same eight-speed PDK dual-clutch transmission, even down to the individual gear ratios.

Where the Turbo and Turbo S E-Hybrid differ from the much cheaper 4 E-Hybrid is in the engine bay, which is now filled by a 4.0L twin-turbo V8. It's a hot-V design, which means the turbochargers live between the rows of cylinders on top of the engine rather than off to either side of the engine block. This has a few benefits. It's more compact, so it can be better packaged in the engine bay. And because the distance that the charged air and exhaust gases have to travel are shorter, the turbines can spool more rapidly, which means better throttle response and less of the dreaded lag.

Other nerdy little engine facts you can use to impress people include the fact that the engine has a square ratio (bore and stroke are both 86mm) and that cylinder deactivation shuts down cylinders two, three, five, and eight to improve fuel economy under the right conditions.

On its own, the V8 provides 550hp and 567lb-ft, which is sufficient to accelerate the 4,486lb (2,034kg) Turbo to 60mph in 3.4 seconds if it's equipped with the Sport Chrono option, or 3.6 seconds if it isn't. (Add 0.2 seconds to both those times for the 0-100km/h times if you only speak metric.) Top speed (on the autobahn, obviously) is 188mph (302km/h).

But in the Turbo S E-Hybrid, the V8 does not act alone. The electric motor, which is located between the engine and transmission, adds an extra 130hp and 295lb-ft to the party, which at least compensates for the heavier (5,126lb/2,325kg) curb weight. In fact, the addition of electric propulsion more than compensates because 0-60mph in this version takes just 3.2 seconds (again, add another 0.2 seconds for the 0-100km/h time). And the top speed is a little higher at 192mph (308km/h), which again is pretty irrelevant to anyone outside of driving distance from an unrestricted German motorway.

But when it comes to driving, the experience is remarkably similar in both cars. After all, the only times most of us perform a standing start up to highway speeds is exiting a toll booth, and few of us are sensitive enough to detect whether we got there in the same time it took a McLaren F1 or 200 milliseconds slower. How the Panamera Turbos feel from behind the wheel depends a lot upon which drive mode you're in.

You access these settings from the little dial that pokes out from the steering wheel's lowest spoke, and it rotates through Normal, Sport, Sport Plus, and in the case of the hybrid, E-Power. In normal, it feels like the car has been dipped in molasses; there's a heaviness about everything. The accelerator pedal needs a hefty shove to get moving. The steering isn't particularly light. You definitely feel the car's mass. Poke it hard, though, and it moves—fast. It also sounds pretty darn good. V8s usually do, and this one has a hard edge to its sound that says, "I'm small and powerful, not big and lazy." (Small being relative to the more massive V8s that you find under the hoods of domestic machines.)

In Sport and Sport Plus, some of that heaviness is gone as the throttle mapping in particular makes the car more eager. But it's never going to feel nimble in the way a much lighter car does. Newtonian physics are like that, even with the optional rear-wheel steering. To get the most out of the car, you need to push the little button in the middle of the mode dial. This is called the "Sport Response button"; it gives you an extra burst of engine power for 20 seconds and puts the suspension and engine into their sportiest settings.

Although one might struggle to differentiate the Turbo from the Turbo S E-Hybrid using the butt dyno, there are easier ways. For one, Porsche's hybrids wear acid green brake calipers and badge highlights (but oddly not seatbelts, even as an option). For another, you'll definitely tell the difference when it's time to fill them up again.

The Turbo has a massive 23.7 gallon (90L) fuel tank, which gives it a hefty 500+ mile (800+km) range. The EPA fuel numbers are 18mpg city, 23mpg highway, and 20mpg combined. Not great, but what you'd probably expect for a 550hp wagon that weighs 2.2 tons. In fact, driving through the wilds of Virginia, where they exhibit almost no tolerance at all for breaking the speed limit, I was able to see 28mpg while cruising at 55mph with the air conditioning running full blast. Conversely, if you want to hoon, as the kids say, prepare to see that number drop down to 10mpg.

The Turbo S E-Hybrid, meanwhile, is rated at 48mpge combined (or 20mpg combined on gas alone, like the non-hybrid). With the same 14.1kWh battery as the cheaper hybrid we reviewed last year, it too will do 14 miles on a full charge. That's perfect for running urban errands or even almost all of the average commuting distance. Recharging the battery takes 12 hours at 120V, or three hours at 240V if you option the ($840) 7.2kW onboard charger.

All the rest of the stuff about living with either Turbo or Turbo S E-Hybrid remains the same as it was for the Panamera 4 E-Hybrid last year. The cabin continues to be extremely well put together, with comfortable sports seats that adjust 14 different ways in the front. The Turbo S E-Hybrid was even specced with eight-way rear power seats ($2,310) and both front and rear seat ventilation ($2,040, but you also get massaging front seats for that). If you and three other people have to spend some time sitting in traffic on a hot day, that's probably $4,350 well spent.

The infotainment system is also identical. As part of Volkswagen Group, Porsche gets access to the MIB 2 platform, which continues to be the best infotainment OS in our experience. (Interestingly, VW Group just announced that it's joining Automotive Grade Linux and the Linux Foundation, which we presume will underpin MIB 3.) The tile-based home screen is highly configurable, but I prefer Audi's Virtual Cockpit to the two smaller displays embedded in the main instrument panel in front of the driver.

Although both cars are the Sport Turismo body style, they do differ when it comes to cargo volume. The Panamera Turbo has 18.3 cubic feet (518L) with the rear seats in use, or 49 cubic feet (1,388L) when you fold the rear seats flat. But the Panamera Turbo S E-Hybrid drops that to 15 cubic feet (425L) and 45.7 cubic feet (1,295L) respectively—the lost space is given over to lithium-ion.

I do have a few nitpicks about the interiors, though. For one, the steering wheel rim is narrow in depth but quite wide, which feels a bit weird. And on a hot day, beware—if you've left the car parked in the sun, the metal paddle shifters behind the wheel can heat up to the point where they will burn your fingers.

As to which one I'd pick, that really depends. They're both stupendously fast, but they're also stupendously expensive. For some people, buying the most expensive Panamera they can is the point, in which case, get the one with all the horsepower and the super-long name. The fact that it's also a hybrid means that for some of the time, you're not killing the planet. For everyone else, my recommendation is… neither. The Panamera 4 E-Hybrid Sport Turismo we reviewed last year is, for day-to-day use, almost as fast, goes as far on a charged battery, and starting at $106,900, is nearly half the price.