Lexus RX 400h
Overview
RX 400h - Launched 2005
When the RX 400h luxury SUV was launched it marked a bold and decisive step into the future of intelligent high-performance motoring. The RX 400h resolved an age-old paradox by making sporting high performance, low fuel consumption and reduced emissions compatible.
- 3.3-litre V6 petrol engine and two powerful electric motors
- Maximum output from the Hybrid Synergy Drive® - 269 Bhp
- Lowest premium petrol SUV fuel consumption today: 34.9 mpg in the combined cycle
- Company car drivers face a Benefit in Kind tax liability of just 23% compared to its rivals, most of whom are at 35%
OSAMU SADAKATA, CHIEF ENGINEER, LEXUS RX 400h
"Conventional wisdom says that high driving performance and superior fuel efficiency cannot be achieved in the same vehicle. We have proven that wisdom wrong with the RX 400h, and taken SUV driving to a new and different dimension."
Performance
- Maximum output from the Hybrid Synergy Drive® - 269bhp
- Top speed - 124mph
- 0-62mph acceleration - 7.6 seconds
- Combined cycle - 34.9mpg
- CO2 - 192g/km of carbon dioxide
- Nitrogen oxides emissions - near-zero
Lexus Hybrid Drive
The RX 400h’s Hybrid Synergy Drive system combines a 3.3-litre V6 petrol engine with a 165bhp front electric motor that has a world’s-best power to weight and volume ratio, a high voltage battery and a generator. A second electric motor at the rear axle gives the vehicle an electric four-wheel drive capability – E-Four – that is automatically engaged when required.
In any journey, the system will operate in different modes in order to maintain the maximum efficiency, with power from the engine, the electric motors or a combination of both. Whenever the vehicle comes to a halt, the engine will automatically be switched off to minimise fuel consumption.
The RX 400h can run on its electric motors alone at start-up and low to mid-range speeds, which cuts exhaust emissions to zero. In normal driving conditions, a power split device will divide output from the engine between driving the wheels and powering the generator, which in turn charges the high-voltage battery. This means the vehicle never has to be off the road to be charged.
Further energy is gained during braking or declaration with the electric motors operating as high output generators to recover kinetic energy that would usually be lost as heat and storing it as electricity in the high-voltage battery.
Hybrid Synergy Drive In Operation
- The RX 400h’s powerful Hybrid Synergy Drive system has key characteristics that contribute to its strong fuel efficiency and driving performance
- Energy loss reduction: the system automatically stops the engine at low vehicle speeds and at idle, so saving energy that would normally be lost
- Energy recovery and re-use: kinetic energy that would usually be lost as heat during deceleration and braking is recovered as electric energy and used to power the starter and electric motor
- Motor assist: the electric motor assists the engine during acceleration
- High-efficiency operational control: the system maximises overall efficiency by using the electric motor to power the vehicle in driving conditions where engine efficiency is low.
When engine efficiency is high, it generates electricity Seamless acceleration: smooth acceleration is a characteristic of the RX 400h’s continuously variable transmission (CVT). In the course of any journey, the Hybrid Synergy Drive system will operate in several different modes in order to maximise efficiency. When the engine is cold and the ignition is switched on, the system will start the engine to warm the unit. Whenever the vehicle comes to rest, the engine stops automatically to conserve fuel.
In low-efficiency conditions, such as during start-up and at low to mid-range speeds, the RX 400h will run on its electric motors alone, thus reducing CO2 emissions to zero.
In normal driving conditions, engine output is divided by a power split device, both to drive the wheels directly and also to power the generator. In turn, the generator drives the electric motors and simultaneously charges the high-voltage battery. In such circumstances, the allocation of power is constantly monitored and adjusted between the engine and motors to maintain the highest efficiency. When sudden acceleration is required, the engine and electric motors again work together with extra power from the battery to boost response.