Everyone and his dog is buying a hybrid car. Should you?

The sales figures for hybrid vehicles are going bananas. The June 2022 sales figures for passenger vehicle registrations in the UK were divided up like this:

  • Petrol     44%
  • Diesel    5.7%
  • Battery electric vehicles   16.1%
  • Mild hybrids  28.7%
  • Plug-in hybrids  5.5%

Apart from the fact that diesel is now less popular than an infectious disease, what’s striking is that over half of the passenger cars sold in the UK in June incorporated some sort of battery power. Blimey.

But just because everyone and his dog is now in a hybrid doesn’t mean they’re always the best choice — and that’s why we’re going on a two-part voyage exploring hybrid pros and hybrid cons. Ready?

Flavours of hybrid

With hybrid vehicles, the first thing to get your head around is that they come in several different flavours. The main types are:

  • Mild hybrids (MHEV). These use a 48V electric motor/generator to assist the petrol or diesel engine under  spirited acceleration. Mild hybrids may use engine start-stop, cutting the ignition when you’re not moving, rolling or braking. Some models recoup energy when braking (regenrative braking). The two key points about MHEVs are that they can’t run under battery power alone and there’s no plug. In fact, MHEVs are so similar to conventional ICE vehicles that owners may not even realise they’re driving one.
  • Hybrid electric vehicles (HEV). Just to make life difficult, these are also called full hybrids and parallel hybrids. Unlike the MHEV, the electric motor is capable of powering the car without any fossil fuel help, though only for very short distances. It also turns on automatically to assist the internal combustion engine when optimal to do so. The electricity is generated from the conventional engine and from regenerative braking, so like the MHEV, there’s no plug involved. Annoyingly, Toyota and Lexus have decided to call these self-charging hybrids, but in reality every HEV is self-charging. Maybe they feel they’ve earned the right to call it what they want, given that they came up with the ground-breaking and popular HEV, the Toyota Prius.
  • Plug-in electric hybrid (PHEV). Here, the clue is in the name: this is the type of hybrid that you have to plug in. Or rather, you have to plug them in to get any hybrid benefits – more on this later. PHEVs have a much larger battery capacity than the other two types, which enables them to run for much greater distances purely on electric power — at the moment, pure electric range is around 15 – 50 miles. After that, you’re back to internal combustion power, though note that in most PHEVs the conventional engine will also fire up when you accelerate hard, and maybe when you use the air-con or heating.

In addition to these,  range-extending vehicles run completely on battery power until that runs out, at which point the combustion engine is used like a generator to power the electric motor. The prime example would be the most popular variant of BMW’s now discontinued ID3.

With that out of the way, let’s start looking at some of the hybrid vehicle’s pros and cons. As most articles about hybrids begin with economy, we’ll buck the trend and start with their environmental credentials.

Hybrids and environmental pros and cons

Hybrid manufacturers love to surf the green wave, filling their telly and other ads with eco-friendly imagery. But do the claims of cleaner, more climate-friendly motoring stack up?

On the plus side:

Hybrids of all sorts do offer lower emissions than conventional ICE (internal combustion engine) vehicles – under certain conditions.

You might think that MHEVs would only deliver piddling emission reductions, but actually these can be substantial. We’ve seen various figures bandied about, but one simulation predicts an 18.5% reduction in fuel use, with the corresponding drop in emissions.

PHEVs have the potential to deliver huge emissions reductions. Given that the average car journey in the UK is 8.4 miles, a PHEV that’s driven gently, on short distances, could theoretically produce zero exhaust emissions – though obviously, you’d need to be getting your electricity from renewable sources.

In the emission stakes, HEVs sit somewhere between MHEVs and PHEVs.

Some emissions experts suggest that hybrids could be a big step forward in tackling climate change. Emissions Analytics, for example, suggest that the world’s limited battery supply would be better invested in a huge number of hybrid vehicles (which are affordable, familiar, and readily available) than a smaller number of battery electric vehicles (BEV). Of course, at an individual level, that doesn’t mean that a hybrid car beats any BEV.

On the minus side:

Although PHEVs have the potential to deliver much lower emissions, that depends on them being driven as decribed above. In the real world, they usually aren’t. If you use a hybrid on longer distances, and don’t accelerate like your gran, then essentially you’re driving a very heavy petrol/diesel vehicle. Any emissions advantages then evaporate: in fact, one study found that PHEVs typically emit about 2.5 times more CO2 than the manufacturers estimate. Other studies have found that many drivers never even charge up the battery.

As for the view that hybrids are a useful stepping stone to BEVs, it’s an argument that drives most scientists bonkers. It’s like, they say, choosing to bail out a sinking boat with a slightly larger egg-cup, when what we need is a bucket. In addition, critics of the motor industry point out that hybrids are a convenient way of doing the minimum possible, hanging onto their legacy products until the bitter end.


Environmentally speaking, a PHEV only offers benefits for certain types of driver. MEVs are a better bet, though they’re a disappearing breed. MHEVs are surprisingly good, in that they offer emissions reductions without having to be mindful about their use. But to be clear, through their vehicle life-cyle, hybrids leave a much heavier carbon footprint than BEVs.

Stay tuned for Part Two, when we’ll look at costs of hybrids, fuel economy and more!

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