Automotive

Citroen C4 Cactus Airflow chases 141 mpg

The Cactus Airflow in its natural environment - the wind tunnel
The Cactus Airflow in its natural environment - the wind tunnel
View 21 Images
The C4 Cactus Airflow achieves 141 mpg
1/21
The C4 Cactus Airflow achieves 141 mpg
Rear-mirrors have been scrapped for slimline cameras
2/21
Rear-mirrors have been scrapped for slimline cameras
Deflectors channel the air around the car
3/21
Deflectors channel the air around the car
The car's wheels feature flaps controlled by centrifugal force
4/21
The car's wheels feature flaps controlled by centrifugal force
The Cactus' panoramic sunroof is made of lightweight polycarbonate
5/21
The Cactus' panoramic sunroof is made of lightweight polycarbonate
LED headlamps save energy
6/21
LED headlamps save energy
The Cactus' signature Airbump pads are made of composite
7/21
The Cactus' signature Airbump pads are made of composite
The car uses a hybrid drivetrain to keep consumption low
8/21
The car uses a hybrid drivetrain to keep consumption low
A longer rear spoiler helps combat turbulence
9/21
A longer rear spoiler helps combat turbulence
Three variable air intakes channel air to the engine when its needed, and keep a smooth profile when its not
10/21
Three variable air intakes channel air to the engine when its needed, and keep a smooth profile when its not
Citroen's aero enhancements are highlighted in orange
11/21
Citroen's aero enhancements are highlighted in orange
The Cactus Airflow Concept is chasing 2l/100km
12/21
The Cactus Airflow Concept is chasing 2l/100km
"ultra ultra" low rolling resistance tires help with fuel economy
13/21
"ultra ultra" low rolling resistance tires help with fuel economy
The Cactus Airflow is also 100 kg lighter than a standard Cactus
14/21
The Cactus Airflow is also 100 kg lighter than a standard Cactus
Aluminum and high-yield steel contribute to the weight savings
15/21
Aluminum and high-yield steel contribute to the weight savings
A rear air-extractor helps cut down on drag
16/21
A rear air-extractor helps cut down on drag
The Cactus hasn't lost its distinctive styling in the transition to a concept
17/21
The Cactus hasn't lost its distinctive styling in the transition to a concept
The car's substructure has also seen changes
18/21
The car's substructure has also seen changes
The floor is now completely smooth to facilitate better aerodynamics
19/21
The floor is now completely smooth to facilitate better aerodynamics
There three drive modes available on the Cactus Airflow
20/21
There three drive modes available on the Cactus Airflow
The Cactus Airflow in its natural environment - the wind tunnel
21/21
The Cactus Airflow in its natural environment - the wind tunnel

Citroen has never been one to follow convention in the automotive world. The French manufacturer is best known for its DS, which coupled pioneering hydro-pneumatic suspension with a gorgeous aerodynamic body to wow crowds at the 1955 Paris Motor Show. Fast forward to 2014 and Citroën is again using the Paris Motor Show to showcase its innovative creations, this time in the form of the C4 Cactus Airflow 2L Concept.

Based on a C4 Cactus SUV, the Airflow is in response to a fuel efficient vehicle program set up by the Plateforme de la Filiere Automobile (Automotive Industry Group) in France. Thanks to a raft of aerodynamic changes and Peugeot/Citroën’s Hybrid Air system, the Cactus Airflow should reach the Industry Group's fuel economy target of 2l/100km (141 mpg).

A rear air-extractor helps cut down on drag
A rear air-extractor helps cut down on drag

If the Airflow moniker didn't give it away, Citroën has paid particular attention to the C4 Cactus' aerodynamics in the quest for better fuel economy. The car's front bumper takes advantage of three variable-geometry air intakes, which constantly adjust to facilitate a smooth profile or let more air into the engine. Mobile air deflectors guide the air flowing around the car, and the car's "Air Curtain" wheels are fitted with shutters that are controlled by centrifugal force.

Not all of the Airflow's aerodynamics are active: small slats fitted to the ends of the front bumper channel air along the wheels and the extended rear spoiler has been coupled with an air-extractor in the rear bumper to cut down on drag-increasing turbulence. The car's underbody has also been made smooth in search of better fuel efficiency.

The car sits on 19 inch “ultra ultra” low rolling resistance tires, which are tall and narrow for optimum aerodynamics.

Rear-mirrors have been scrapped for slimline cameras
Rear-mirrors have been scrapped for slimline cameras

Traditional door mirrors also get the boot on the Cactus concept, with slimline rear-view cameras taking their place.

Overall, Citroën claims its changes (which are painted orange on the car) improve aerodynamic performance by 20 percent.

Another enemy of fuel efficiency is weight, so the Cactus Airflow 2L has been put on a serious diet. Aluminum is used for the inner-side members and rear floorpan, and high-yield steel components replace structural chassis elements like the heel board and front-side rails. These aluminum and high-yield components are supplemented by composites used in the car's floor, and contribute to 100 kg (220 lb) of weight saving, or 11 percent over the standard Cactus.

The floor is now completely smooth to facilitate better aerodynamics
The floor is now completely smooth to facilitate better aerodynamics

As well as lightening the car's structure, Citroën has scattered lightweight components throughout the Cactus. Carbon-composite materials make up the concept's springs, tailgate, rear bench, side panels, roof and roof cross members, wings and doors, while aluminum engine mounts further reduce weight. Even the glass in the car's panoramic sunroof has been replaced by lightweight polycarbonate, a move usually reserved for trackday specials like the RenaultSport Megane.

Power comes from a"Hybrid Air drivetrain, which couples Citroën’s 3-cylinder PureTech engine with a compressed air system to give drivers the choice of three drive modes. In "air power" mode the car is powered by compressed air stored in two composite tanks mounted at the car's rear. When running in petrol-only mode, the Cactus' engine takes advantage of low viscosity oil, carbon-coated moving parts and polymer componentry to reduce fuel-sucking friction, and improves operating efficiency by 5 percent.

The car uses a hybrid drivetrain to keep consumption low
The car uses a hybrid drivetrain to keep consumption low

When combined in hybrid mode, Citröen claims that the Airflow's HybridAir drivetrain improves fuel consumption by 30 percent over running the engine on its own.

The C4 Cactus Airflow Concept will be displayed at the Paris Motor Show, where Gizmag will be on the ground covering all the action.

Source: Citroën

6 comments
Mark A
Where are the US engineers? Come on guys, catch up.
Daishi
@Mark A some of the concepts uses aren't revolutionary they just rarely make it to production vehicles because there are tradeoffs involved like cost, durability, and maintenance. Using compressed air instead of electric/battery in a hybrid system is interesting but there is no way they are getting a sustained 141 MPG out of it especially not out of an SUV. The odds that this thing gets 3 times the mileage of a Prius are effectively 0. If that number was even close to accurate they would be doing absolutely everything in their power to push this technology (hybrid air) into production immediately. They would halt factory production of every other vehicle in their lineup and have everyone in their company work around the clock on this and they could probably get it to production in the next 2 months. I think their claim about hybrid air would seem more valid without making ridiculous claims like 141 MPG but well see how viable it really is after they get it to production.
Milton
@ Mark A: They are working for Tesla. Preparing to launch the Model X. And I imagine they are laughing at the complexity of this ICE / Compressed-Air vehicle. You can't have ICE and efficiency. The aerodynamic work done on this vehicle is awesome, I particularly like the centripetal-force activated wheel-covers. But if efficiency was their main goal, then they should have started by ditching the ICE for EV. Had they done that, they would have experienced phenomenal gains in efficiency before even approaching the topic of aerodynamics. Dressing up an ICE for aerodynamics is a bit like putting lipstick on a pig.
hkmk23
Just two scenarios which make this a bit of a joke. 1. What happens two years down the line when the seals are worn and the compression system and storage start leaking (losing pressure)? 2. Is this system going to collect the polluted air with unburnt diesel and petrol fumes (as in any city) and try and compress this explosive cocktail? That should be interesting (from a safe distance).......!
Riaanh
@Milton, you have the right idea, but unfortunately there is only a couple of hundred engineers working at Tesla. What I am wondering is, what is the thousands of engineers working at GM, Ford and Chrysler doing for fuel consumption?
Slowburn
@ Milton Efficiency doesn't matter when the energy density is so low.