This week at TreeHugger: Lotus has developed a 'sound simulation technology' to make hybrids and electric cars noisier. Since the sound is simulated, you could probably hack it to put in the sound of a TIE Fighter or an old Sherman tank. Oh boy... Nissan has unveiled the ECO Pedal, a tactile feedback mechanism in the gas pedal that helps you save gas. Also, Anchorage, Alaska, will install 16,000 LED streetlights, an investment that could save $360,000 per year at the current energy prices. Technically, the technology that Lotus is using was first developed to make its cars quieter. But in the 'Safe and Sound' Prius prototype and future vehicles, a water-proof speaker is installed in the engine compartment, close to the radiator, and when the car is in electric-mode, sounds is synthesized. "The technology was designed around the behavior of a conventional engine, using an existing engine sound which makes it instantly recognisable with the pitch and frequency helping to identify vehicle distance and speed." With the ECO Pedal, Nissan has come up with a new way to get fuel economy feedback while driving. The way it works is simple. When the system is on, "each time the driver steps on the accelerator, a counter push-back control mechanism is activated if the system detects excess pressure, helping to inform the driver that they could be using more fuel than required." After a while of this pavlovian regime, you can't help but learn which behaviors the car "approves" of and which you should avoid. The municipality of Anchorage (where wild bears roam kids' playgrounds), along with Cree, Inc, a maker of LED lights, are planning to change 16,000 municipal roadway lights with high-efficiency LED fixtures (about 1/4 of total streetlights). TreeHugger's EcoModo column appears every Tuesday on Gizmodo.