New Car verses Old Car

As the economic climate collapses around us, many people are putting off their purchase of a new car and making do with what they already have. Old cars are bad and polluting, new cars are clean and efficient right? So this is a bad thing?

Not necessarily. The SMMT say that the average new car generates 1 tonne of CO2 to build (lets ignore the raw material / recycling arguments for the moment). We also know from the DfT that the average car in the UK travels about 10,000 miles per year.

Let’s say that you haven’t had to sell your children into slavery as a result of the credit crunch, and in fact you’re on the market for a new Mini. Well, let’s just imagine that those people still exist.

BMW as a company has become one of the leaders in the field of fuel efficiency improvement with their so called “mild hybrid” systems. The calculation is shown below:

Carbon Credentials of Minis

Carbon Credentials of Minis

The conclusion then is that to make the CO2 Savings for the base model MINI you have to drive more than 62,000 miles. So after 6 and a bit years you will have made a positive impact on the environment by buying a cleaner car.

So what about the fuel savings? The calculation for the mpg (fuel economy figures) are below as well:

Fuel Credentials of Minis

Fuel Credentials of Minis

Given that the average spend on fuel per year per car is about £1,000, how long would it take to save 10% of that, or £100? Well, 16,000 miles on the base model MINI.

Considering that a base model MINI retailing at about £11,000 and will lose just 15% of it’s value (£1,650) in the first year (it’s the slowest depreciating car you can buy currently), then saving £60 in fuel is pretty minimal.

2007 Mini One

2007 Mini One

Obviously if you decide to replace your 30 mpg petrol car with a similarly priced second hand 40 mpg petrol car, then you can expect to save about £340 and 880kg of CO2. Which is not to be sniffed at, especially when you consider the further savings in tax, insurance and so on.

So should you buy a new car for environmental reasons? Probably not. Buy a smaller second hand car instead. Or learn to drive more efficiently.

2008 Mini One

2008 Mini One

Should you buy a new car to save money on fuel? Definitely not. You’d have to madder than a box of frogs.

Should you buy a new car because you want to? Of course, that’s one the delights of living in a free country. In fact at the moment you’ll probably get a very good deal indeed as most car markers are looking down the barrel of bankruptcy. But just don’t try to justify it for money saving or environmental reasons…

2008 Mclaren F1 CarLet’s compare an F1 car to a typical car in the UK which produces about 160 g/km, and over a year (10,000 miles) will produce about 2.56 tonnes of CO2.

According to Wikipedia a typical F1 burns 75 litres of fuel per 100km raced. Based on figures for petrol (which is a reasonable proxy of race fuel), 0.75 litres of fuel burnt per km equates to a CO2 output of 1737 g/km. And over a race season using approx 100,000 litres of the stuff, that’s 231 tonnes of CO2. Per car. And each team has 2. So for fuel alone, before the costs of flying to races, support vehicles and the number of cows required to furnish Max Mosley’s “special” wardrobe, that’s about 463 tonnes per team. I wonder if they carbon offset?

At least they’re becoming hybrids for the 2009 season…

So here in London, Boris Johnson has announced he’s going to create a cycle scheme along the lines of the Velib in Paris. He may look like Worzel Gummidge’s mad cousin, but I Boris, outside a barber's yesterdaysuspect he’s a very smart cookie. Good on him.

Now, if this scheme were to take off, then potentially less buses or tube trains would be needed (as if there are enough already! – ed), and this could have a beneficial impact on the carbon footprint of London. So what’s might that be?

Well, 6,000 cycles are going to be used in zone 1, so let’s assume that roughly:

  • 25% replace tube journeys* @ 65.0 g/km
  • 25% replace bus journeys* @ 81.8 g/km
  • 25% replace cab journeys @ 172 g/km
  • 25% replace walking journeys @ 0 g/km

A Parisian Street YesterdaySo, assuming cycling is carbon neutral, that’s an average of 79.7 g/km improvement for every passenger km.

Assuming that any bike in use is averaging 5km / hr through central London, and that at any one point averaged throughout the day (more during the day and less at night of course), 30% of the cycles are in use. Then we can assume that at any point then we can assume that 1800 of them are being crashed by lost tourists, and 9000 km being cycled every hour. Over a day that’s 216,000 km pedalled, or 17.2 tonnes of carbon offset every day. That’s pretty good Boris.

However, does anyone else have a sneaking suspicion that the majority of Boris’s bikes will disappear by the truckload and end up in Albania ?

Speed-bump, road hump, speed ramp or sleeping policemen. Let’s face it by any name they are the bane of urban driving (unless of course you make your living selling replacement shock absorbers). They’re a hassle, damage cars and cause urbanites to drive otherwise unnecessary 4x4s (in my experience anyway). Yes, average speeds are reduced, but so is your attention of what’s up ahead as you’re trying not to clout your exhaust on that unnecessary piece of road calming. Other complaints made against them are that they slow down emergency services (endangering lives), they are particularly unhealthy for people with back or neck pain and create noise for local residents.

Speed Humps

Speed Humps

But I can add another one, that they’re giving the poor Polar Bears an early bath. Yup, that speed bump round the corner on Mornington Close is directly responsible for the increasing popularity of bear-centric swimming lessons at the North Pole. So let me tell you how….

The AA (Automobile Association) did a bit of research on fuel consumption for cars at the Millbrook Proving Ground and found that a typical mid-size car running at a constant 30 mph did 58 mpg. However a car slowing down and speeding up for speed bumps only did 31 mpg. Put that into carbon figures* for a petrol car** and you get 113 g/km of CO2 at a constant 30mph, or 211 g/km over speed bumps. So a kilometer of road with speed bumps creates an extra 0.1kg of CO2 for every single car that travels it.

For argument’s sake, lets say this km of road has on a average a car going each way down it every minute during the day and night***. In a year, that means a single stretch of road creates an extra 103 tonnes of unnecessary CO2 per year. We’re making estimates here, but if that km of road has 10 of the UK’s estimated 100,000 speed humps, then speed bumps in Britain are responsible for a colossal 1.03 million tonnes of CO2 per year. That’s about the same as the total carbon footprint of the 830,000 residents of Fiji, or almost twice that of Greenland. Ouch.



You can console yourself that as a UK taxpayer, based on the estimate that 50 standard humps on three or four connecting residential streets costs about £150,000. So the UK speed hump population cost us £300 million pounds. Which is about what Newcastle United would cost you if you wondered up to St James’ Park with a really big chequebook this morning.

*Clear research

** A diesel car is actually worse with 128 v 240 g/km

*** More in the day and less at night of course

More information here.

You want to be environmentally conscious right? Reduce your carbon footprint, do the right thing and save the polar bears? But in the back of your mind, you’ve always wanted that sports car you could never afford. That present you’d always promised yourself. But sports cars aren’t exactly the environment’s best friend are they? Can you really have the best of both worlds?

A Green Porsche

A Green Porsche

Well the answer is yes, and to demonstrate how I’m going to use two flatmates, Vegetarian Sam and Capitalist Rufus. They both work in central London, live in the suburbs and both require non-public transport at weekends, holiday in the same place and have very similar lifestyles. The only difference between them is the transport choices they make.

Sam takes the train (60.2g/km*) and bus (67.8g/km*) to work everyday. He has a 6 year old Ford Focus 1.8 TDCi (145 g/km*) which he drives at weekends.

Rufus rides a scooter (Vespa 50cc @ 72g/km**) to work and at weekends and refuses to use public transport. He (cue much teeth-sucking disapproval) also has a Porsche Boxster (227 g/km* for the weekends). And let’s try not to hate him just because he has a Porsche. Let’s pretend he uses it at the weekends to take old people to the seaside.

Sam and Rufus work in the same office everyday do exactly the same distance each year, so how can Rufus, the Porsche-driving capitalist scum be greener than his vegetarian, flip-flop wearing flatmate?

The Commute:

Sam and Rufus both travel from Clapham Junction to Liverpool Street every day. Sam takes the train to Waterloo (6.3km = 0.76 kg CO2) then the bus for (4.8 km = 0.65 kg CO2) giving a total of 1.41 kg per return journey.

Rufus goes direct door to door on his Vespa which is 8.9 km (compared to Sam’s 11.1km), producing 1.28 kg of CO2 for his return journey.

The Weekend:

Sam and Rufus both travel at the weekends, and they each rack up 4,000 miles per year driving in some form. Sam does all his miles in his Focus (934kg of CO2), whereas Rufus does 1,500 of these in his beloved Porsche taking old people to the seaside (548 kg of CO2), while the other 2,500 he does on his trusty scooter (290 kg of CO2), a grand total of 838kg.

The Total:

So where does that leave us?

CO2 Footprint Commute*** Weekends Total

Sam 310 kg 934 kg 1,244 kg

Rufus 282 kg 838 kg 1,120 kg

So vegetarian Sam takes public transport to work every day, drives an efficient diesel car but still has a 10% bigger carbon footprint than capitalist Rufus and his petrol guzzling Porsche even though they travel exactly the same distance.

So can you be green and drive a Porsche? Looks like it. It just goes to show that it’s not quite as simple as it seems to condone sports cars….


* / VCA car fuel data.

** Clear analysis

*** 220 days a year

Sports cars. With the exception of the real die-hard lentil sandal wearing environ-mentalists, most people love the idea of a sports car. But admit that at an Islington dinner party and it’s about as PC as claiming you’re Osama Bin Laden’s tennis partner. So can you really have a green sports car?

A blue green car

A blue green car

Arguably the greatest ever car designer was a chap called Colin Chapman who founded Lotus. His most famous quote on making fast cars was “Simplify and add lightness”. He also said “Any car which holds together for a whole race is too heavy”, but let’s not worry about that right now. Chapman believed that to make a car faster you make it lighter. If a car is lighter, then you need smaller brakes, a smaller engine, smaller tyres and so on to get the same level of performance. Which means the car is lighter still, creating a rather nice virtuous circle. You also save fuel costs, for example reducing the weight of a car by 100kg will save you about 900 litres of fuel over it’s lifetime*. That’s about £1,200 at today’s fuel prices. Then again you could also argue that by cutting down on the burgers and losing 10 kg, that would save you £120!

Chapman sadly died in 1982, but I suspect he’s turning in his grave as he sees how bloated and overweight cars have become. What’s frightening is the statistic that although the average weight of a car in Europe is around 1,200 kg, in the US it is 2,000 kg. In the last 25 years since his death, the average weight of cars has increased by 60% in some classes**. And cars on average are getting heavier by 16kg every year***.

Very interesting, but what relevance does this have to CO2 or that lovely sports car you want? Well, to get a car to any speed you need to add energy. 0.5 x the mass of the car x the speed**** (squared) to be exact. Halve the weight of the car, and you halve the energy needed, and halve the fuel required to get to that speed, and the amount of CO2 that gets produced as well.

The same is true with speed as well, except the amount of energy required is squared. So to get 100mph requires 4 times the energy to get to 50mph. Admittedly once you’re at speed, then the aerodynamics play more of a part in how much fuel is burnt (and CO2 that is produced), but lets concentrate on the weight for now.

The trouble with this kinetic energy is that when you slow down it’s changed into heat in the brakes, and it’s gone. This is where regenerative braking comes in. Hybrids and Electric cars can use their motors as generators and save this energy to use again. But they’re still thin on the ground, and unless you have £100,000 for a Tesla Roadster ( you’re out of luck if you want a sports car.

So where does that leave us? Well, funnily enough where we started with Lotus. Generally 2 seater sports cars tend to weigh in between 1,200 and 1,500kg*****. A Lotus Elise in 1996 weighed just 720kg. Even now with airbags, safety equipment and crumple zones it weighs about 900kg. That means it needs a smaller engine, brakes and so on to give the same performance. And that also means less CO2.

As an example, a £140,000 Ferrari 430 will hit 60mph in 4 seconds and produce 420 g/km of CO2. A £32,000 Lotus Elise SC will hit 60 in 4.4 seconds and produce 202 g/km. Which is less than a bog standard Volvo estate.

So there you go. If you want to go green, but still want a sports car, then buy a Lotus.


** Source: SMMT


**** Speed in metres per second

*****eg: Porsche 911 – 1,400kg, Ferrari 430 – 1,450kg, Porsche Boxster 1,420 kg, Honda S2000 1,274kg

Source: Clear research

The Clear Business Tool

Its a question any responsible managing director should currently be asking, and Clear have created a calculator to enable you to measure it. And best of all it’s free. No charges, no catches.

Many companies offset carbon footprint measurement, but the quality of results can be extremely variable. As a carbon offsetter, Clear Offset believes that the first step to reducing your carbon footprint is being able to measure it. And companies are less likely to do this if it costs £000s in consultancy fees. So we took all the knowledge we had, put it in a carbon auditing tool and gave it to the world for free. And best of all, it’s entirely compatible with DEFRA / The UK Government’s Quality Assured Offsetting Scheme.

So help yourself – the tool can be found here:

and let us know what you think…