Hybrid v electric – what’s the difference and what should you look for?
We are, whether we like it or not, right now in a transition period between one epoch of motoring history and the next. Up until now, from the day Bertha Benz took her husband Karl’s Patent Motorwagen out for a spin, cars have been powered by reciprocating pistons driving a crankshaft, drawing their power from tiny explosions of dead dinosaurs.
In the not-very-distant future, that will be passé, and cars will be powered by silent, hopefully sustainable electricity, but right now we’re at the crossover point. Petrol and diesel cars are at a peak of efficiency and cost-effectiveness, electric cars are still expensive and more limited in their capabilities, for the most part. So is a hybrid the best of both worlds?
Way back in 1997, both Honda and Toyota launched hybrid vehicles on the road within months of each other, and they were the first hybrids ever to go on sale to the public. Honda’s was the sci-fi looking Insight — a two-door coupe with smooth aerodynamics and a futuristic shape. Toyota’s was the first Prius, a boxy four-door with batteries slung under the boot and a gutless 1.5-litre petrol engine doing most of the work. One was fascinating, the other a touch dull, but guess which one sold better?
Twenty years on, hybrids are at last coming into their own, thanks to tireless development work. Toyota has stuck firm by its hybrid system layout, the Toyota Hybrid Synergy Drive, and while the details of the current setup are different, the overall layout is the same as found in that first generation Prius.
So, you get a petrol engine of varying size — in the Yaris Hybrid is a 1.5, in the Prius and in the Auris and CH-R Hybrid it’s a 1.8, while Lexus uses bigger 2.5-litre four-cylinder or 3.5-litre six-cylinder units for its hybrids. Along with the petrol engines is a pair of electric motor-generators, one that primarily does the driving and one that mostly acts as a dynamo to recharge the battery stack as you drive.
Toyota has thus far stuck by heavy, old-fashioned nickel batteries rather than the more fashionable, faster-charging lithium-ion ones (basically the same technology as in your laptop or mobile), because the Japanese company reckons that the nickel batteries are more reliable in the longer term, and it has been proved right by the sheer number of Priuses still happily cruising about.
The petrol engines are usually tuned to run on what’s called the Atkinson cycle, which is pretty much the same intake-compression-ignition-exhaust cycle as a conventional petrol engine, but with a longer intake-valve lift duration, which artificially increases the engine’s stroke, making it more fuel efficient, if less powerful. That’s where the electric motor comes in, adding extra power and torque to cover up the Atkinson cycle’s power deficiency.
Of course, there are other benefits, not least the fact that the electric motor is powerful enough to drive the car by itself, so you can drive for short bursts on just electric power around town, dramatically reducing your urban fuel consumption and emissions rating.
The downside of all this is that the motors and batteries add a lot of weight, which is bad for handling and acceleration, and on longer motorway journeys, they’re essentially dead weight. This used to cripple economy on long runs (we remember an especially torturous trip in the Prius+ MPV, which averaged less than 30mpg on a motorway run), but Toyota has tweaked and improved the hybrid and its often-controversial CVT transmission and now a current Prius can easily crack the 60mpg mark on the motorway.
Others use basically the same setup, but with nuanced differences. Hyundai’s Ioniq Hybrid and the Kia Niro, for example, use a 1.6-litre petrol engine with a six-speed dual-clutch automatic transmission, which is supposed to be more enthusiastic to drive than the Prius’ CVT, but which in reality is actually pretty similar. The benefit is the same, though — improved economy and emissions, without the need the plug in and charge up.
Of course, you can have a hybrid that plugs in, the imaginatively-named plug-in hybrid. Mitsubishi was really the first to catch this wave, with the Outlander PHEV. The idea is obviously tempting. Plug in and fully charge the battery stack and you can drive around for up to 50km on just the electric motor, emitting nothing and keeping your local Green Party councillor happy. For longer journeys, you have a conventional petrol engine and a small fuel tank on board, which frees you from the tyranny of ‘range anxiety’ (that creeping sensation that you haven’t got enough battery charge to make it to your destination). Either way, you benefit from low CO2 emissions — the Outlander, in spite of being a chunky, roomy SUV, has emissions of just 49g/km, for example.
Pretty much every other manufacturer has followed suit and launched a plug-in hybrid. Audi, Mercedes-Benz, BMW, Volkswagen, Porsche, Volvo, Kia, Hyundai and the rest are all scrambling to bring their own plug-ins to market. The appeal is obvious and theoretically a plug-in hybrid makes the most sense right now — you get away from the bad publicity of diesel emissions, keep an ultra-low CO2 rating with its attendant tax benefits and still have a normal engine and fuel tank for when you want to venture out of town.
The devil is in the details, though, and the fact is that plug-in hybrids are much harder to extract proper fuel economy from than their hybrid counterparts. If you’re making full and maximum use of the batteries, charging up regularly and only very occasionally using the petrol engine, then you should do OK. Those with higher mileages are on a hiding to nothing, though — we’ve driven more than a few plug-in hybrids that struggled to do better than 21mpg, and even the best (BMW’s 330e, Volkswagen’s Golf GTE) won’t do much better than 50mpg on longer journeys. Toyota is this year launching a new Prius Plugin, which scores an official 22g/km of CO2 and goes for 48km on just the batteries.
So maybe you should go fully-electric? Well, yes, you should because eventually you’re going to have to, but right now, most electric cars don’t have enough one-charge range to suit most of our lifestyles. If you’re genuinely a townie, who does little or no rural mileage, and likes to take the train for longer hauls, then great — an electric car is perfect for you.
Longer runs? Well, that’s tricky. You can buy a Tesla Model S with a theoretical one-charge range of more than 600km, but in reality, even from that €100k luxury electric car, you’re going to do well to squeeze more than 400km from it.
Down at a more affordable level, the current best three electric cars are the Hyundai Ioniq, the BMW i3 and the Renault Zoe. An updated version of the Zoe promises 400km between charge-ups, but realistically you’re going to need to plug in again after 250km. BMW makes a realistic claim of 200km for the all-electric i3 (though you can buy a version with a tiny petrol engine that keeps the batteries topped up on longer journeys, which can give you an extra 120km of range when you need it) and Hyundai says that the Ioniq Electric will do 280km, but again 200km is a more realistic prospect.
The thing is that you would be surprised how practical these three cars are in day-to-day driving. The Renault’s extra range means that you could do even a long haul without stopping for a fast-charge, and even if the BMW and Hyundai need more regular top-ups, the fact is that the ESB fast-charging network is actually pretty good, and gives you an excuse to stop for a coffee. Yes, driving a pure electric car right now still requires a bit more advance planning than you’d do for a diesel or petrol car, but it’s getting easier all the time and the benefits in terms of emissions, and the sheer joy of driving a silent, smooth electric car, are there to see.
So, to sum up, if you want to get a foot on the electric car ladder, a conventional hybrid is the easiest, most painless, and most cost-effective solution. Plug-in hybrids require a little more effort, substantially more cost and really are best kept in town. Pure electric cars are catching up fast on both though, and with a little thought and attention to detail, more and more of us really could switch to an all-battery car.