Vauxhall Ampera - Any Colour but Green!

Sunday 17th July, 2011
It's that time of year again where many different journalists, representing even more different publications, attend the overseas launch of a new "eco" car and all somehow end up writing up the same facts, from the same press briefing, alongside photos from the same USB stick. This time, it was the exciting launch of the Vauxhall Ampera.

I wasn't there myself, I had my Ampera first drive at the Michelin Challenge Bibendum event in May, but this time attendees were apparently told amazing facts like under 40g/km of CO2, charging time of under 4 hours and some rather insane combined fuel economy figure of more than 176mpg. Naturally, as I did with the Nissan Leaf, I've done a few sums of my own.

It would seem the Vauxhall Ampera is being marketed as one of these wonderful new electric eco cars. Sold in the US as the Chevrolet Volt, it's the first of a new type of vehicle known as the Extended Range Electric Vehicle or E-REV - notice how they split of the E to make it look that little bit more eco? I expect on some marketing leaflet somewhere, they'll make that first E green and lower case, just to make it even cooler. It will probably go on to win a load of so called "Green Car Awards" but I digress.

The Background

For the most part, the Ampera is just another electric car with around 400lbs of batteries scattered around what might normally be the transmission tunnel of the car. If you're sat in the back, they disguise this by removing the middle seat and replacing with a cup holder unit. The obvious disadvantage is that you can only seat 4 people but it does mean very few compromises in other areas of the car. Essentially it looks a lot like a normal car, it drives a lot like a normal car and has the space of a normal car. Of course, there's a reason for that - it's no better than a normal car - just because somebody tells you something is low emission or eco doesn't actually mean that it is.
The main issue with EVs is that they usually have a rather limited range - such as our old friend the Nissan LEAF which, despite being sold for £30,990, will still only go around 100 miles on a full charge. Nissan get around this limitation at events where charging facilities aren't available by carrying around a Honda portable generator like this one to create the electricity they need from unleaded petrol - and that's basically how an E-REV works. Vauxhall drop a 1.4litre engine under the bonnet and, as the batteries run down, the engine kicks in to charge them back up - except they don't call it an engine, they refer to it as a "petrol-fuelled electric generator" to try and focus attention to the fact that the car is only powered by the batteries and not by the engine. Well, not usually anyway, unless you happen to run out of batteries whilst driving uphill - as they can't quite charge the batteries fast enough, they need to temporarily power the wheels directly like a normal car. Of course, most people call a car that will run on batteries until they're flat and then start the engine a hybrid...but we're supposed to call this one an E-REV because it's different, ok?

The Analysis

Like most EV manufacturers, Vauxhall like to claim that the car will create zero emissions when running on battery alone - carefully ignoring how that charge actually got there. Citing the usual kind of "80% of journeys are less than 30 miles" style statistics, they claim the Ampera "can drive 50 miles on electricity alone, with zero tailpipe emissions" - which I'm sure it can, but does it? In reality, I understand the battery management system will actually only let the batteries get down to 20% before the engine starts - allowing only a 40 mile drive before the exhaust pipe starts throwing emissions out and in "mountain mode", the battery even tries to stay above 40% decreasing that range further still.

But let's look at these 50 "emission free" miles a little closer. If you remember, on the "zero emissions" Nissan LEAF, we calculated a figure of around 81g/km CO2 based on average National Grid emissions. So how does the Ampera compare? Well, pretty badly really.

The LEAF will go around 100 miles on a full charge of its 24kWh of batteries. The Ampera, however, will only do just 50 miles (assuming that engine doesn't kick in) on 16kWh of batteries. Yes, 75% of the batteries, 50% of the range. Naturally this affects the emissions it creates rather significantly. Using my best buddy the NEF CO2 calculator, we can work out that 16kWh of electricity (assuming no additional losses whilst charging) will emit 9kg of CO2, based on average UK Grid emissions. So 9kg for 50 miles = 180g per mile or, if we divide by 1.6, 112.5g/km CO2.

113g/km...for an eco car? That's not band A, not even B, we should actually be into VED band C territory here. Proof, if any were needed, that we should take power station CO2 into account for electric vehicles. As it is, this will likely be treated as a "green" car and therefore exempt from car tax, exempt from the London Congestion Charge and qualify for significant advantages over others as a company car. Sure it'll be cheap, but if you want a low emission electric car...maybe you should go and ask Renault about the Fluence.


According to Vauxhall, "recharging is easy: the lithium ion battery can be charged from a 230V socket in under 4 hours." This too, has me rather curious. You see, the power socket in your home will deliver a maximum power of 3kW but, for safety, appliances usually limit this to around 2.2kWh. Even if it did pull the full 3kW, we have to deliver 16kWh to fully charge the batteries. It doesn't take Isaac Newton's maths talent to figure out that this equates to 5hrs 20mins - at the more likely 2.2kW, this extends to over 7 hours - rather longer than the claimed less than 4.

Even if you go as far as fitting a £1000 16 Amp EVSE (special socket) on your house, and it delivers a full 230V at 16 Amps, it's still going to take 4 hours 20 mins so a FULL charge in under 4 hours is just never, ever, going to happen.

But of course, you'll never need that FULL charge because that battery management system will never let the battery charge fall below 20%. So you'll only likely ever need a maximum of 12kWh...possibly less. Delivering this charge at 3kW an hour looks rather more possible in 4 hours, certainly so with an EVSE, but surely this just confirms that the battery only range is actually 40 miles not 50? Either it can use it for range, and you'll need to put it back in from the power socket in over 4 hours, or you can't use it for battery only range and the quoted figure should be less. You can't have it both ways.

Fuel Economy

According to the manufacturer, "With the Vauxhall Ampera you can go up to 50 miles on its battery alone and up to another 310 miles extended range with the 1.4 litre (82 HP) petrol-fuelled electric generator." They further go on to claim "the combination of battery power and extended range technology deliver up to 175 miles per gallon of fuel whilst emitting less than 40g/km of CO2".

Some bold claims there, the latter based on the official ECE R101 Test Cycle. Of course, should this be true, something doesn't really add up. If it really can do 175 miles on one gallon of fuel, and has a petrol range of 310 miles, then surely it only needs a 2 gallon (9 litre) fuel tank? Then why does it in fact need a whopping 35 litres to achieve this?

In fact, assuming the first 50 of the 175 miles were electric only, this would imply that one gallon of fuel actually only got the car 125 miles. Still an impressive claim though, if it were possible. As it is, Vauxhall are claiming a max range of 310miles on 30-35 litres of unleaded (Vauxhall don't seem to publish the fuel tank size) - which equates to just 40-45mpg, rather less. Petrol cars with this kind of fuel economy usually fall around the 160-170g/km CO2 level (VED Band G/H) so I look forward to seeing official emissions figures for this car.

In the US, the EPA measured the Chevrolet Volt (basically the same car with different styling) at just 37mpg in petrol-only mode which, with UK gallons being 20% larger, makes my theory about right.


Ultimately, once you blow away the eco smoke screen, this car offers the world nothing over a normal car. It tries, but fails, to be an efficient electric car yet has a carbon footprint in EV mode that is around 30% higher than those already on the market. When the batteries run out, a petrol engine kicks in to extend the range but, as it has 180kg of batteries and an electric motor to haul around too, this isn't particularly efficient either.

I used to argue, having studied the drive-train, that this car should be called a hybrid, not an E-REV. But applying the word hybrid to a model generally means that the vehicle might be more efficient and have some of the lowest emissions in its class - with an apparent best case scenario of around 45mpg and a carbon footprint for each journey that will likely never fall below 112g/km CO2, neither of these apply here.

To top it all, they want to charge £33,995 for one which is about £10k more than a similar sized Toyota Prius which easily achieves a real world 60mpg and an official rating of 89g/km. Remind me again why a recession hit Government is offering £5000 of tax payer's money to discount cars like this?

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