Read sales brochures for new cars and you'll quickly reach tech overload. The level of gadgetry packed into vehicles these days is stunning, if not overwhelming. From lithium-ion batteries to voice-activated navigation to HDMI video inputs, the specs on many modern automobiles can read more like high-end electronics than anything you might commute in. Some of the stuff is really cool and gets a lot of attention, like gee-whiz infotainment systems and the nannies that keep you from wandering into another lane or running down some hapless pedestrian. But cars are loaded with subtler technologies that quietly go about their jobs without drawing attention. In fact, there's a good chance that you don't even know your car's got some of this hidden tech giving you more power, better fuel economy or a more comfortable slog through your commute. It's surprising that in many cases the underlying technology has been around for years, waiting for modern manufacturing, materials or computer controls to fulfill their promise. Some upgrades are making their way from high-end luxury cars to the masses. And some take existing technology and give it an unexpected twist for a surprising result. Here are 10 examples that make life behind the wheel just a bit safer, more convenient or more efficient. Above: Direct injection It used to be that choosing an engine was easy. You could have powerful engine with lousy fuel economy or a wheezer with fantastic fuel economy. It's always been a lousy choice, but its even more so as consumers demand more oomph and the government demands more efficiency. Direct injection gives you better power and better fuel economy at the same time. This twist on fuel injection squirts fuel directly into the combustion chamber instead of the intake manifold. This allows the engine computer to deliver exactly the right amount of fuel into the chamber, rather than guessing how much will make it past the intake valves. The result is less wasted fuel, and since the injector can "swirl" the fuel mist perfectly, it's optimized to burn in the best possible way for more power and torque. Direct injection was used in fighter planes during World War II, and the awesome Mercedes-Benz 300 SL used it in the 1950s. But it didn't really take off in the auto biz until 2000 or so, and it has grown increasingly popular as automakers try to meet tightening fuel economy and emissions regulations. Photo: John Baisden assembles an engine at Cleveland Engine Plant No. 1, which cranks out the company's turbocharged direct-injected EcoBoost engines./Ford

Active Noise Cancellation Traditionally, there have been two ways to combat road and wind noise. The first was to swaddle the interior with insulation, muffling outside noises. Trouble is, that adds a lot of weight, and weight is the enemy of fuel economy. The second method, which is no less effective, was to simply crank up the radio. Now there's a third way, which riffs on the crank-it-up method. A growing number of automobiles use active noise cancellation, much like you find in the headphones everyone wore on your last flight. The technology uses the car's audio system to cancel out unwanted sound waves. A microphone "listens" for certain sounds or frequencies. A computer recreates that sound using an anti-phase wave. When the offending sound wave meets its anti-phase counterpart, they cancel each other out, allowing you to revel in the glorious sound of ... anything but the humming of tires, the rumbling of the road or the droning of the engine. Like so much cool tech, active noise cancellation first appeared in luxury sedans, but now you'll find it in more pedestrian fare like the GMC Terrain. Image: The active noise-canceling system in the 2011 GMC Terrain, explained./General Motors

Electric Power Steering A vehicle's engine does more than just move the car around. It also runs the air-conditioning compressor, alternator and power-steering pump. That's a lot of work, and it creates a lot of drag. Drag is bad. It makes your engine work harder, which really hurts your fuel economy. One way to reduce this drag, and therefore increase fuel economy, is to electrify the pumps driven by the engine. One of the first to go is the hydraulic power-steering pump. Small, powerful electric motors can drive the hydraulic pump, or directly assist the steering without any hydraulics at all. Either way, the engine gets a break, allowing it to make more power and use less fuel. The first electric power steering system appeared in the Acura NSX in 1990. Nowadays, you'll find the tech in hybrids, electric vehicles and many passenger cars like the BMW Z4 (shown). Photo: BMW

Hydrocarbon-Sensing Climate Control So there you are, stuck behind a big rig when it belches a blast of diesel exhaust. The acrid smell fills your car, reminding you that you'd left the air conditioning set to "fresh air" instead of "recirculate." By then it's much too late, and your car smells like the parking lot at a truck stop. People who spend big money for luxury cars don't have this problem. A growing number of high-end autos have a carbon filter and hydrocarbon sensor. The electronic nose constantly sniffs the air. When it detects a pollutant, it automatically switches the climate-control system to "recirculate" to spare your air. It isn't perfect -- you're outta luck if someone's squashed a skunk, for example -- but it's a pretty cool feature just the same. Photo:A Mercedes-Benz engineer tests an air conditioning unit./Daimler

GPS Climate Control It seemed like there wasn't much more to be done with climate control after dual-zone systems ended the "I'm hot!" vs. "I'm cold!" argument by letting the driver and passenger set their own temperature. But the newest thing in climate control is linking the system to the car's GPS. The global positioning system already knows where the car is and which way it's pointing; add the date and time and -- voila! -- the car can tell where the sun is located in relation to the car. That means it can custom tailor the climate control as the car moves closer to, or further from, direct sunlight. Yes, it's probably just as effective to reach over and turn the knob yourself, but that's not nearly so cool, is it? Photo: The Acura RL will keep that chap comfy with its GPS-assisted climate control./Honda

Acoustic Glass You wouldn't think there'd be much R&D in something so mundane as glass. But in their quest to build ever-quieter cars, manufacturers are looking long and hard at the windows. High-end cars typically feature side and door windows of specialized sound-deadening glass. By sandwiching a thin layer of sound-damping vinyl between two panes of glass, less noise is transmitted to the interior. It's a surprisingly easy way to reduce cabin noise, and it's appearing in less expensive cars like the Chevrolet Malibu (shown). Photo: Bobbi Ralston signs off on a on Chevrolet Malibu at the end of the assembly line at the General Motors Fairfax Kansas Plant./General Motors

Magnetorheological Dampers Shock absorbers generally come one of two ways: Soft for ride comfort or stiff for handling. Oh sure, there are adjustable shocks that let you tweak those settings manually, but this the computer age. That should be done automatically, on the fly. Turns out it is, if you've got a car fitted with magnetorheological dampers. Magnetorheological dampers are filled with oil containing microscopic particles. These particles bind together in the presence of a magnetic field, thickening the oil and making the shock firmer. Sensors monitor the compression and expansion of the shock, automatically adjusting the viscosity of the oil to account for what the car is doing. Cruising along a smooth freeway? The magnetic field created by an electromagnet is weaker, the fluid thinner and the ride pillow-soft. Swerve to avoid a critter in the road or hammer a winding back road and the shock stiffens to provide a firmer, more controlled ride. You'll find the tech in sports cars like the Ferrari 458 (shown) and the Audi R8, along with sportyish vehicles like the Acura MDX. Photo: Ferrari

Multiplex Wiring Harnesses Once upon a time, automobiles were relatively simple contraptions with relatively simple features and relatively simple wiring harnesses like the one shown above. As cars grew increasingly complex, so too did the wiring that was needed to power a rising number of accessories. Modern cars are filled with hundreds of sensors, circuits and electronic components. The wiring harnesses required to power all that stuff would be a nightmare without multiplexing. Multiplexing — sending multiple signals across a single wire or sensor — is nothing new; telephones have been multiplexed for decades. But it is relatively new to the auto industry as it packs cars with more high-tech features, not to mention power windows, power locks, heated seats and even tiny refrigerators. By reducing the number of wires running from your car's computer to the engine, audio system, climate control and other electronic components, automakers reduce weight, improve quality, save money, and make it easier to add still more stuff in the future.

Solar Cells We're still a long way from ever seeing solar cells actually powering our cars, but photovoltaics are making their way into modern automobiles. The Toyota Prius uses them to power the fan in the climate-control system while the car is parked. That keeps the interior cool, reducing the need to crank up the A/C when you get in. The electric Nissan Leaf (shown) sports a small cell on the rear wing to trickle-charge the 12-volt battery. It doesn't send any juice to the cars' 24-kilowatt-hour lithium-ion pack, though. Photo: Nissan