As we know,
plants absorb carbon dioxide and then breathe out oxygen,
so why not put plants in the exhaust system of your car?
Impossible? Well, Alan Titchmarsh might say so, but what does he know?
What we have here is a Range Rover,
which now has the same 5-litre V8 that you get in the Jag.
At the back, we have tubes which take the exhaust gases
into this greenhouse, which is full of plants.
Tomato plants on this occasion,
and that means the tailpipes emit no greenhouse gasses at all.
What you're looking at here, ladies and gentlemen, is the future.
It really is impossible to over-emphasise the importance
of what has been achieved here today.
Look at what I'm driving,
a big heavy thirsty four-wheel-drive car,
and the only waste product is some juicy tomatos.
You thought greenpeace would save the world, but no!
It's Top Gear. We've done it.
Was it cool?
What? Why are they applauding?
I don't know, but there's a little bit of glass on the road.
Yeah, brilliant. Top Gear would have saved the planet
except you smashed the green-house.
I admit it didn't go brilliantly.
You also said that you weren't giving off any greenhouse emissions at all.
-Yes. -Well, that's rubbish,
because you only had a hundred tomato plants.
How many tomato plants do you need to get rid of the emissions from a Range Rover?
Four hundred thousand.
-Seriously? -Yes, we've worked this out.
To accommodate that many, your greenhouse would have to be six miles long.
Do you know I can tell why you two aren't astronauts?
-Hey. -No s--
Who here has seen Apollo 13? Hands up. You know what I'm all about.
That bit when Houston telephones the guys, the astronauts, in the spacecraft
because the CO2, the carbon dioxide, is building up.
"We need to build something to get rid of it". Remember?
Yes, good. These two would just turn, "We're a little bit cold and frightened.
We can't". Whereas I am Commander Jim Lovell.
I didn't...I didn't give up after my greenhouse failure,
came, back rolled up my sleeves and came up with another idea.
-Oh God. -No.
We fire up the Jag, right?
Lovely. Now what we've got here is a gas-o-metre. Okay?
And its prong is up that exhaust, and what's it's telling me is that
15 per cent of the gas coming out of this exhaust pipe is carbon dioxide.
Okay? Come here and verify that for me.
-It's actually 14.5 per cent, yes? -Okay, yes.
Right.
Take the prong out, because on this side, on this tailpipe, I've modified it.
I've got tubes feeding into this Apollo 13 homemade filter,
which is... it's full of lime soda crystals,
which they used to absorb the carbon dioxide
in those huge Australian mines, okay.
So, we're going to pop the prong in the top because as you can see,
the gas is going down there, through the crystals, out of here.
Let's just have a look how much carbon dioxide that's producing.
It's none. What? Nothing? None.
Absolutely no carbon dioxide is coming out of that car.
Wow!
Now, I know we have a reputation on Top Gear
for cocking about, okay, but on this occasion, we aren't.
This is not a Toyota price. It's not a stupid gee whiz.
It's got a 5-litre supercharged V8,
and all that's coming out of this tailpipe is nitrogen and oxygen, which is...
-Hang on a sec. -What?
-These little rocks of yours. -Yes.
-They absorb the carbon dioxide. -They absorb it, yes.
So how far can you go before they get all clogged up
and they can't absorb any more coming out?
On a motorway, six miles.
With something that size, yes.
How much does it cost for a new box of rocks?
-75 pounds. -Oh God.
Look, I know Barnes Wallis had setbacks, but he persevered,
and I'm sure if science can make genetically modified weed,
they can make those absorb more.
I really do think that we're onto something here.