I also seem to remember that the audio system was specially designed to consume less power (although it's too friggin hot around here to look it up).
EDIT: OK I did look it up... Lot of stuff here, including the audio bits.
From:
http://www.autoguide.com/auto-news/2010/09/lexus-ct200h-gets-134-hp-42-mpg-average.html
ENERGY SAVING AND ENVIRONMENTAL PERFORMANCE
Air Conditioning Performance
Allowing for independent control of left and right hand sides of the cabin, the new CT 200h is equipped with a compact, lightweight air conditioning unit incorporating a powerful, electric, variable capacity compressor. The use of a hybrid battery-powered electric compressor reduces the load on the engine, improving fuel economy, whilst the surplus power of the unit allows it run below full capacity, with greater efficiency and with less noise.
The integrated-inverter electric compressor contains a centrifugal oil separator that removes oil from the refrigerant, reducing the amount of oil escaping from the compressor. This allows for a more efficient refrigerant cycle, optimizing the air conditioning’s cooling performance.
The use of a lightweight, MF (Multi Flow)-IV sub cool condenser reduces refrigerant volume to further improve system efficiency. And the characteristics of the brushless blower motor have been refined to suppress noise whilst delivering a large volume of cool air.
Exhaust Heat Recirculation System
Because of the need to heat the cabin and de-fog the windscreen, hybrid vehicles can suffer a drop in fuel economy during winter months. To counter this, Lexus engineers have incorporated a third generation exhaust heat recirculation system.
The exhaust heat recirculation system helps the engine coolant reach normal operating temperature more rapidly by circulating it around a section of exhaust pipe. This not only improves fuel efficiency by reducing the time needed for the engine to warm up, allowing the Lexus Hybrid Drive system to shut of the engine sooner, but also enables the 495 watt Positive Temperature Coefficient (PTC) heater to provide warm cabin air more quickly in winter.
LED Lighting
Lexus was the first automotive company to introduce LED headlamps for low beam use, with the LS 600h L in 2007. Consuming 45 percent less power than conventional, halogen units, they offer an improvement in fuel economy, perfectly complimenting the energy saving efficiency of Lexus Hybrid Drive.
With available LED headlamps, up to 46 LEDs are used in front, eight used for the door mirror-mounted turn indicators and 35 in the rear, the CT 200h is equipped with no less than 89 external LEDs –the largest number yet fitted to a Lexus model.
Lexus Audio System Amplifier
An available, energy efficient, Digital Signal Processing-integrated (DSP), eight-channel, full range class D amplifier makes its first appearance in the CT 200h. The new DSP unit consumes 50 percent less power than a conventional, analogue-powered amplifier and, with its weight reduced from 2.9 lbs. to 2.1 lbs., is 26 percent lighter.
Bio-sourced Materials and Bamboo Charcoal Speakers
Improving its environmental performance, several of the CT 200h’s larger components including the loadspace deck sides, deck board and deck board trim have been fabricated from a bioplastic material containing 30 percent plant-based polyethylene terephthalate. The new full hybrid also benefits from an easy-to-dismantle construction, and recycle marks have been placed on the front, rear and tailgate trim to facilitate optimum recycling.
A Lexus and industry first, both sound systems are equipped with unique, bamboo charcoal-based resin diaphragm speakers. Constructed using a complex compound combining bamboo charcoal, bamboo fiber and resin, the diaphragms are injection-molded to a thickness of only 0.008-0.01 in., and are some 10-15 percent lighter than a conventional speaker diaphragm.
