Audi Introduces Metroproject Quattro Sub-Compact Plug-In Hybrid Concept at Tokyo Show
24 October 2007
|The Audi metroproject quattro.|
Audi is unveiling the metroproject quattro, an original Audi design study for the sub-compact segment, at the Tokyo Motor Show.
The concept features a plug-in hybrid drive. A 1.4-liter TFSI engine developing 110 kW (148hp) powers the front wheels by means of the S-tronic Direct Shift Gearbox. A 30 kW (40 hp) electric motor positioned on the rear axle is able to deliver up to an additional 200 Nm of torque when the vehicle is accelerating. The differential compensates for any slip on one side.
The 1.4-liter TFSI and turbocharger is an advanced version of the unit that made its series production debut in the Audi A3 a few months ago. Whereas the 1.4 TFSI musters 92 kW (123 hp) in the A3, it delivers 110 kW (148 hp) at 5,500 rpm in the study. Its peak torque of 240 Nm is on tap over a broad rev band from 1,600 – 4,000 rpm.
Multi-hole injectors result in very homogeneous mixture formation and extremely efficient combustion. This is also an effective means of helping to cut pollutant emissions. The integrated turbocharger promises optimized responsiveness and torque build-up. Eighty percent of peak torque can be summoned up from as low down as 1,250 rpm—barely above idle.
The electric motor can power the vehicle alone for zero-emission driving. A lithium-ion battery pack supports a range of up to 100 km (62 miles) in pure electric mode; the battery pack can be recharged from any power socket. The combustion engine only cuts in again once battery state of charge has dropped to below 20%. In electric mode, the car has a top speed of more than 100 km/h (62 mph).
When the two drive units are working in unison, however, the Audi metroproject is transformed into a genuine quattro with combined torque of 440 Nm in total (240 Nm from the 1.4 TFSI plus an extra 200 Nm from the electric motor).
The automatic start/stop facility, energy regeneration and phases of purely electrical operation reduce the fuel consumption and emissions of the Audi metroproject quattro by around 15% compared to when it is running exclusively on the combustion engine. Despite its performance (0-100 km/h in 7.8 seconds, top speed of 201 km/h), the study consumes 4.9 liters/100km (48 mpg US) in mixed mode operation, while CO2 emissions average 112 g/km.
The Audi metroproject quattro is equipped with the same Audi drive select system that can be ordered as an option for the current generation of the Audi A4. This enables the driver to pre-select one of two specially adapted configurations for the drivetrain, shift characteristics and magnetic ride shock absorbers.
The default setting is the “efficiency” mode, which is automatically activated every time the engine is started. In this mode, the engine and transmission respond gently to use of the accelerator and shift paddles. This setting is intended for a relaxed driving style, as well as lowering fuel consumption and emissions.
The “dynamic” mode is designed to produce a dynamic driving sensation. In this mode, the vehicle’s electronics also harness the torque available from the electric motor to achieve extra-sporty acceleration along with excellent lateral dynamics.
I wonder what's the top-speed in all-electric mode.
Posted by: Alain | 24 October 2007 at 04:37 AM
Posted by: Skrivo | 24 October 2007 at 04:54 AM
I'm not keen on the aluminum rails supporting the roof, they remind me of the Citroen Pluriel (whose roof can be removed). They're also incongruous with the overly aggressive front and rear facia. IMHO, this car is trying a little too hard to hide its small size. Then again, they had to differentiate it from VW's rather bland New Small Family (cp. Up! and Space Up! concepts).
Note that Audi chose the same hybrid layout (parallel through-the-road) they used for the original Avant Duo, the first modern production hybrid. Sadly, the battery, power electronics and control systems technology of the day wasn't up to the task and the Duo flopped badly in the German market.
However, PHEV layouts really only make sense for urban runabouts and commute vehicles, which aren't supposed to cost an arm and a leg. Does it really need a 150hp turbocharged ICE? Wouldn't a 50km (30mi) range on grid electricity be quite sufficient in most cases, using cheap carbon foam lead-acid batteries (Firefly) rather than fancy Li-ion units? Plus, with a beefy electric motor to mask torque loss during gear shifts, wouldn't a single-clutch manumatic be good enough?
The mere fact that you have useful range and performance on grid electricity alone *is* the premium. There's no need to go overboard, though I suspect the marketing departments at GM, Volvo, Citroen and Audi are all keen to skim the cream off the top before they take the technology mainstream.
Posted by: Rafael Seidl | 24 October 2007 at 06:14 AM
I want one.
Posted by: Eric S | 24 October 2007 at 06:20 AM
Design is good and concept is also good. Audi was the first to make a Hybrid, but they never brought it to the market.
Is the Lithium battery good now, if so when are they bringing it to market.
Posted by: Max Reid | 24 October 2007 at 07:58 AM
Last time I talked to the guys at firefly they said there batteries were a year away from production
Posted by: | 24 October 2007 at 07:59 AM
i want one!
Posted by: itsme | 24 October 2007 at 08:23 AM
If Firefly is a year from production, they should have some evaluation units by now. Audi may not have the luxury of waiting. Then again, none of the Li-ion manufacturers is already shipping in high volume, either.
All I'm saying is VW AG may want to have more than one traction battery technology option in the medium term.
Posted by: Rafael Seidl | 24 October 2007 at 08:28 AM
I agree with you.
The customers should have more options for battery packs, from a low power, lower cost Firefly to the most sofisticated high performance, high cost lithium pack with ultra capacitors. In other words, we should have the choice between PHEV-30, 60 up to 100+ Km. Ideally, the battery pack should upgrable, at a latter date, when cost is down.
Posted by: Harvey D | 24 October 2007 at 09:35 AM
I'm thinking that the electric motor could use at least another 10kw. My Camry has 105kw. At 30kw I'd think the gas motor would kick in at even mild acceleration. If you wanted to do a short trip on battery only you'd need a third "electric only" setting.
Posted by: HenryP | 24 October 2007 at 10:22 AM
I want one too, if it were reasonably priced. 60 miles all-electric would cover almost all my driving. Plus it's not too agro in looks on the one hand while not being too wimpy-looking on the other. Friendly-sporty, not mean-sporty, if you know what I mean. But as Rafael suggests, I'd cut some of the performance to keep the price down.
Posted by: Jeff R | 24 October 2007 at 12:01 PM
You get the same gas mileage in the new A3 Sportback 1.9 TDi. Plus you get five doors and a decent boot in a very popular package...
I guess Audi is trying to say that their customers can have their cake and eat it too with this concept.
For adequate cruising speed, a 50 kW ICE would suffice (to around 100 mph / 160 km/h) and the 30 kW motor could supplement for acceleration on the highway and/or temporary higher speeds. But if the marketing dept. insists that they need a little extra to entice customers, just add 20% to those figures...
Posted by: Thomas Pedersen | 24 October 2007 at 12:49 PM
HenryP: You can cruise at highway speeds with less than 15kw. Here's an interesting article on PHEVs
Posted by: Neil | 24 October 2007 at 03:35 PM
People in urban environments who would need a small vehicle (me) to get to work, don't have room to store a larger vehicle for recreation, and so tend to want to purchase a vehicle which can be more general purpose.
Hybrid vehicles have a much greater utility than pure electric vehicles, and more importantly allow the owners to use them as a freedom enabling device which a pure electric vehicle does not do.
A pure electric vehicle requires planning.
Posted by: Michael McMillan | 24 October 2007 at 05:10 PM
@ Henry P -
note that electric motors can be overtorqued for short periods (~30 secs) due to the thermal inertia of the rotor and stator. In other words, an electric motor rated at 30kW = 50hp can actually deliver perhaps 50kW = 80hp for short bursts of acceleration and/or recuperative braking, provided the battery and power electronics can also support that load. Moreover, permanent-magnet motors can deliver close to rated torque at any speed and instantly - an ICE cannot hope to match those dynamics. Acceleration response at low vehicle speeds is what drivers of urban runabouts care about most.
In short, don't directly compare electric horsepower ratings to those for ICEs. In transient situations, which are the norm in light duty vehicle applications, the two are chalk and cheese.
Btw: 30kW = 50hp sustained is about what you need to keep moving at 75mph = 120kph on the freeway. Audi has wisely advertised a top speed of just 100kph on grid electricity alone to avoid excessive wear and tear on the electrical components. Your light duty ICE wouldn't last 150,000 miles either if it were always driven at or near peak load.
Posted by: Rafael Seidl | 25 October 2007 at 11:09 AM
1hp is approx 746W so 50kW is closer to 67hp.
What is "thermal inertia" of an electric motor?
Posted by: Patrick | 25 October 2007 at 12:07 PM
@ Patrick -
sorry, you're right. I had miscalculated on the conversions.
Thermal inertia simply refers to the time it takes for a mass to heat up. Electric motors aren't 100% efficient, some of the energy is dissipated due to ohmic resistance and eddy currents induced by the fluctuating magnetic field strength. Many traction motors feature a cooling fan.
Overtorqueing an electric motor means increasing the current to levels that will cause the windings to self-heat faster than they can be cooled. Do it for too long and the wires or rather, the insulation around them, melts. This destroys the motor.
Posted by: Rafael Seidl | 25 October 2007 at 01:31 PM
Yes, I am aware of eddy currents and the small resistances of a motor I just had never heard the term thermal inertia applied to electronics before but I specialize in communications and not electromagnetics.
Posted by: Patrick | 25 October 2007 at 02:29 PM
30kW sustained is about what you need to keep moving at 75mph = 120kph on the freeway.
A small car needs only about half that on level highway with no wind, but long highway grades can easily triple the road load.
The idea of 100 km pure EV range with a 30 kW motor is silly, though. Even with overtorque the power is simply insufficient for highway merging, gradability, etc. The ICE will kick on for all but the most benign driving, just as it does in Prius PHEV conversions. And, as you note, the ICE in this concept car is oversized -- 110 kW electric and 30 kW ICE would make more sense.
I think Firefly is a lot more than one year away from their full battery design. A year sounds about right for their first phase.
Posted by: doggydogworld | 26 October 2007 at 06:36 AM