Toyota reduces fuel consumption and emissions across the new Auris range; 13% average reduction in CO2 compared to predecessors; gasoline, diesel and hybrid
Toyota is unveiling its new Auris for the European market (earlier post), representing its first step in a product offensive in the European C-Segment. Aerodynamic improvements, weight savings and engine enhancements have reduced fuel consumption and CO2 emissions across the range. Toyota anticipates a 1/3 full hybrid, 1/3 gasoline, 1/3 diesel engine mix.
Average emissions for Auris—which is designed for the European market—have fallen steadily over the last years. When the first generation Auris was launched in 2007, the average emissions were 152 g/km. This fell to 142 g/km in 2009, and then down to 125 g/km in 2011 after the pioneering full hybrid version was introduced. With the launch of the new Auris, the average CO2 emissions level will drop to 109 g/km, a further 13% reduction on average compared to the previous generation.
The new Auris will be built at Toyota Motor Manufacturing UK (TMUK) alongside the Avensis. Toyota is the world’s leading producer of C-segment vehicles, with 39 million units sold in more than 140 countries since the introduction of the Corolla in 1966. The launch of the Auris Hybrid in 2010 (earlier post) made Toyota the first manufacturer to offer a choice of three powertrains in the C-segment.
Powertrains. The new Auris’ powertrain line-up, which now features a choice of an improved full hybrid or two gasoline and two diesel engines offering the performance- and economy-enhancing benefits of Toyota Optimal Drive. The 1/3, 1/3, 13 powertrain mix not only demonstrates the wide range of customer choice the line-up brings, but also that full hybrid is a mainstream proposition, accessible to the largest possible audience—i.e., not a niche solution, according to Toyota.
Toyota Optimal Drive showcases a combination of wide-ranging advanced technologies and internal improvement programs designed to optimize the balance of performance and driving enjoyment with fuel economy and low emissions. These diverse core technologies focus on three key aspects of powertrain development:
The reduction of powertrain weight through the use of super-lightweight and highly compact engine components and transmissions throughout the new Auris engine range.
The minimization of mechanical losses through the adoption of Valvematic—a further development of VVT-i—in the 1.6 gasoline engine, new roller rocker technology and smaller, lighter pistons in both gasoline engines, low viscosity oil and 6-speed manual transmissions throughout the new Auris engine range.
The maximization of combustion efficiency. This has been achieved within the new Auris gasoline engine range through the use of high, 11.5:1 compression ratios, Valvematic, the refinement of intake port and combustion chamber design and piston cooling by oil jet. All new Auris diesel engines benefit from low compression ratios, optimized combustion chamber dimensions and enhanced Exhaust Gas Recirculation (EGR) cooler efficiency.
1.33l Dual VVT-i. Featuring Stop & Start technology, the 1.33-liter gasoline engine is equipped with Dual Variable Valve Timing-intelligent (VVT-i) and a high compression ratio of 11.5:1, which increases the thermal efficiency of the engine. It generates 73 kW/ 99 DIN hp and maximum torque of 128 N·m (94 lb-ft) at 3,800 rpm.
Fuel consumption is 5.4 l/100 km (43.6 mpg US) with CO2 emissions from 125 g/km, a reduction of 0.4 l/100km and 11 g/km versus the outgoing model.
Benefitting from Toyota’s motorsport experience, the small-bore, long-stroke unit is lightweight and compact, improving the vehicle’s power-to-weight ratio. It features a resin-type cylinder head cover and intake manifold, and the intake channel has been streamlined to optimise airflow for improved combustion efficiency.
Dual VVT-i helps boost response levels across the entire rev range by varying the air-fuel intake and exhaust valve timing to suit the conditions at any given time. In addition to improving torque at low and medium engine speeds, the system also reduces emissions and enhances fuel efficiency.
1.6l Valvematic gasoline engine. Valvematic is a further development of Toyota’s Dual Variable Valve Timing-intelligent (Dual VVT-i) system. Valvematic takes VVT-i technology a step forward by adding lift and duration control to the inlet valve variable timing. This improves intake airflow volume and speed management—and, subsequently, combustion process management—to deliver more power for less fuel consumption, with reduced CO2 emissions. The adoption of Valvematic further reduces friction and pumping losses under light engine loads, further lowering fuel consumption.
Valvematic efficiency is further improved through the adoption of a variable length inlet manifold. This acts as an accelerator at low to medium engine speeds, maximizing inlet air speed for optimum combustion efficiency. At higher engine speeds the manifold is fully open. This allows air to travel via a shorter route, maximizing the volume of air entering the combustion chamber and, hence, engine power output.
Available with either a six-speed manual or MultiDrive S automatic transmission, the 1.6-liter Valvematic engine develops 97 kW / 132 DIN hp and a maximum torque of 160 N·m (118 lb-ft) at 4,400 rpm. When equipped with the manual transmission, the unit returns a combined cycle fuel consumption of 5.9 l/100 km (40 mpg US) and generates CO2 emissions of 138 g/km—reductions of 0.7 l/100km and 12 g/km. MultiDrive S transmission further reduces both fuel consumption and emissions, to 5.7 l/100 km (41.3 mpg US) and 134 g/km respectively.
1.4l D-4D diesel engine. Available with either a six-speed manual or six-speed MultiMode transmission, the 1.4 liter D-4D engine develops 66 kW / 90 DIN hp and maximum torque of 205 N·m (151 lb-ft) at 1,800 to 2,800 rpm.
The 1.4 D-4D 90 turbodiesel unit also benefits from improved Toyota Optimal Drive technology, maximizing performance and driveability while minimizing fuel consumption, and CO2 and particulate emissions.
A new 2-step hydraulic control valve is installed in the timing chain cover. This has the benefit of reducing friction when hydraulic pressure is low by opening and closing the relief valve based on driving conditions.
Engine warm-up time is minimized through the installation of a new coolant by-pass system that helps to reduce heat losses in engine coolant during start-up.
New generation piezoelectric injectors control the fuel volume and the timing of the injection more accurately. The high speed reaction time of Piezo injectors makes multi-phase high speed injection possible. This has the effect of both lowering the rate of combustion expansion and effecting a more thorough burn within the combustion chamber, thus further reducing particulate, NOx and CO2 emissions.
This, allied to higher common rail injection pressures of 160 Mpa, results in shorter injection times, combining a faster engine response with improved fuel economy and reduced CO2 emissions.
When equipped with the manual transmission and Stop & Start technology, the improved 1.4 D-4D 90 unit returns a combined cycle fuel consumption of 3.8 l/100 km (62 mpg US) and generates CO2 emissions of 99 g/km—a reduction of 0.6 l/100km and 10 g/km.
2.0l D-4D diesel engine. Mated to a six-speed manual transmission, the 124 DIN hp 2.0 liter D-4D turbodiesel engine has been extensively revised and now features Stop & Start technology as standard.
The unit features a new turbocharger with a lower friction bearing system and an electric actuator. CO2 emission-reducing lubrication and cooling circuit improvements include a 2-stage pressure oil pump with improved oil jet, an optimized water pump with a reduced flow rate, and a twin-chamber oil pan to improve engine warming speeds.
Exhaust emissions are further lowered through a new glow plug control strategy and improvements to the construction and coating of the DPF.
The use of a resin cylinder head cover, oil cooler bracket and water pipe reduce engine weight by 3 kg. The reduction of friction through the adoption of a low-friction vacuum pump, a low-friction timing chain and low-viscosity oil further enhance fuel efficiency. Combustion improvement through a new piston bowl shape and the new glow strategy has perceptibly lowered engine NVH.
As a result, the engine is quieter, torque delivery has improved and CO2 emissions have been lowered by 19%—from 138 to 112 g/km on the combined cycle. Fuel consumption has also fallen from 5.2 to 4.3 l/100 km (54.7 mpg US) over the combined cycle.
MultiMode transmission. Available on the 1.4 D-4D 90 diesel version of the new Auris, MultiMode is an automated manual transmission with a fully automatic shift mode and no clutch pedal. It offers the driver a choice of two fully automatic gear change modes or a manual, sequential gear change with steering wheel-mounted shift paddles.
Selecting E (Economy), M (Manual) or R (Reverse) allows the car to creep in the manner of a conventional automatic. In E mode, the car makes automatic gear shifts that will maximize fuel economy. Selecting ES (Sport) mode will delay changing up to a higher rpm, giving a more sporting style of drive.
MultiDrive S transmission. Available on the 1.6 Valvematic gasoline version of the new Auris, MultiDrive S is a continuously-variable transmission (CVT) with a fully automatic seamless shift mode or a sequential, stepped 7-speed Sport mode.
In automatic mode, the system is optimized for quietness and fuel economy, precisely matching the transmission to the engine at all times by monitoring accelerator pedal angle, vehicle speed and braking force.
In Sport mode, the system is optimized for response and direct engine control. The stepped 7-speed CVT performs close ratio upshifts and has a direct downshift feeling and braking and deceleration.
Sport mode also features precise cornering control. Upon detecting deceleration, the system downshifts and applies engine braking to assist the braking force. Mid-corner, the system suspends shifting when lateral G-force is detected. On corner exit, predictive downshift logic controls the system to ensure the optimal gear ratio is selected for required level of acceleration.
Stop & Start technology. Available with the 1.33 liter Dual VVT-i gasoline engine and the 1.4 liter D-4D diesel engine and fitted as standard on the 2.0 liter D-4D diesel engine, Toyota’s Stop & Start system automatically switches off the engine when the vehicle is stopped. Featuring an immediate restart with virtually no engine sound or vibration, the system delivers reductions in CO2 emissions during urban driving, and can lower average fuel consumption by up to 3%, depending on driving conditions.
Stop & Start automatically stops the engine when the shift lever is moved to the neutral position and the clutch pedal is released, enhancing fuel economy. The engine will automatically restart, within less than half a second, when the clutch pedal is depressed.
Toyota Stop & Start technology allows for the continued operation of the air-conditioning system. With the air-conditioning in use, the engine will not stop if the desired cabin temperature has not been reached. When that temperature is reached, the air-conditioner will switch to ‘ECO-run loading’, allowing the engine to automatically stop. The engine will automatically restart in the event of low battery charge, or if the vehicle begins to move, in the interest of safety.
In conjunction with the Stop & Start system, an ‘ECO’ indicator will illuminate during every automatic stop. An ECO counter also displays the elapsed time of stops during each drive, and a re-settable ECO odo-counter displays the vehicle’s total accumulated idling stop time.
Full hybrid. Designed for the European market and built at Toyota Motor Manufacturing UK, the Auris Hybrid was launched in 2010, making Toyota the only manufacturer to offer a choice of three powertrains in the C-segment. Since its launch some 60,000 full hybrid versions of the Auris have been sold, making it the second-most popular full hybrid in Europe, after the Prius.
The new Auris Hybrid’s HSD powertrain features improvements to further enhance Toyota’s unique, full hybrid driving experience. The control logic of the Hybrid Synergy Drive system’s planetary gear transmission has been modified to give a smoother, more natural feeling to vehicle acceleration, with a closer relationship between vehicle speed and engine revs.
Capable of operating both independently and in combination, the HSD system’s 1.8 liter VVT-i petrol engine and 60 kW electric motor generate a maximum power output of 136 DIN hp (101 kW), equipping the Auris Hybrid with a 0-100 km/h acceleration time of 10.9 seconds and a maximum speed of 180 km/h (112 mph).
With improved aerodynamic performance and lighter weight of this next generation model, the Auris Hybrid’s CO2 emissions have improved to below 89 g/km (with 15” wheels). In addition, the Auris Hybrid generates significantly lower NOx and NO particulate emissions than diesel engined cars of comparable performance.
The Auris Hybrid can run in EV mode for up to 2 km (1.2 miles) at speeds of up to about 50 km/h (51 mph), dependent on battery charge and driving conditions.
Auris Hybrid models benefit from a repackaging of the battery pack under the rear seat, and luggage capacity is now equivalent to that of other models in the range.
Aerodynamics and weight. At 4,275 mm the overall length of the new Auris has increased by 30 mm, though its wheelbase remains the same at 2,600 mm. The front and rear overhangs have both increased by 15 mm, and the Auris remains one of the most compact cars in its class.
The frontal projected surface area of Auris has been reduced by 4% over the current model and, without impacting on passenger accommodation, its overall height lowered by 55 mm (the cabin by 45 mm and the ride height by 10 mm), making it one of the lowest vehicles in the segment. In combination, these changes offer considerable aerodynamic benefits, contributing to improved fuel efficiency and driving dynamics.
In conjunction with a lowering of ride height by 10 mm, equal attention has been paid to ensuring the smoothest possible airflow beneath the new Auris. The underfloor features a front spoiler, a lower absorber, an engine undercover, front spats, centre floor undercovers, tank side floor undercovers, a rear floor undercover and rear spats to maximise aerodynamic efficiency.
This underfloor aerodynamic performance is further enhanced through the positioning of wing-shaped vertical wings to the centre and rear floor undercovers, further smoothing the air flow under the vehicle to promote greater handling and high-speed stability.
As a result of the comprehensive aerodynamic measures, the new Auris’ coefficient of drag has been reduced from Cd 0.292 to Cd 0.28.
The extensive use of high tensile steel in the bodyshell construction helped to reduce the overall weight of the new Auris by up to 40 kg, while its overall reduction in height has also lowered the center of gravity.
The Electric Power Steering (EPS) has also been improved. The steering column benefits from a more rigid attachment to ensure a linear steering feel, a new EPS control suppresses changes in steering force for improved linearity and a high gear ratio provides greater steering response. In all, these revisions equip the EPS with more directness, better feedback and quicker turn for greater vehicle agility.