The Popular Science Automotive Buyer's Guide

You shouldn't need a degree in computer science to understand what’s going on under the hood of your next car. Here's your no-nonsense guide to the latest automotive -- and the coolest cars that showcase them

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Table of Contents:
Power To Go Engines ........................| 1
Handling The Road Braking and Traction ........................| 2
Managing Power Transmissions ........................| 3
Information Access Driver Interfaces ........................| 4

Should you get a turbocharged four or a high-tech hybrid? A slick seven-speed automatic or a sequential manual? Will all-wheel drive really save your butt? You probably already know what type of vehicle you want--SUV, sedan, sports car--but understanding key automotive technologies in today's cars can help you decide among competing models. Here, we dissect the critical innovations manufacturers are offering to enhance performance, safety or both.

POWER TO GO | ENGINES

Don't let the showroom jargon scare you. The internal combustion engine still works as it always has; it's just better. Modern refinements can make a huge difference in initial cost as well as operating cost, raising or lowering either, but they also greatly improve performance. Depending on the specific model and price, engines may have any of several enhancements--these are the four you should know about.

How many cylinders do you need?
For basic fuel efficiency, four-cylinder engines rule. But for real acceleration and easy cruising at high speed, get a turbocharged four, a six-cylinder or an eight. And a Hyundai V6 is nothing like an Audi V6--the simpler (and cheaper) 3.5-liter engine in Hyundai's XG350 produces 194 horses, while the 3.2-liter power plant in the Audi A6 employs sophisticated engine-management systems to help generate 255 horsepower. In any case, you can stop at a V8--there are a handful of cars with V12s being sold in America, but there's little they can do that a well-engineered V8 can't, except make outrageous howling noises and gulp gas like it's shooting out of a garden hose.

1.Variable Displacement
Tech
To improve gas mileage at highway speeds, certain engines can now deactivate half their cylinders--or just two. While the pistons continue to move inside the cylinders, fuel intake is shut off.

Pacesetter
Honda Odyssey. The sophisticated 255-horsepower 3.5-liter V6 in the Odyssey smoothly shuts down three of its six cylinders during highway cruising and deceleration, bumping up mileage by as much as 12 percent.

Other Options
Variable displacement works in muscle cars, too. The Dodge Magnum RT's 340hp, 5.7-liter V8--as well as other Dodge and Chrysler Hemi engines--features a multi-displacement system that boosts fuel economy by 5 to 20 percent.

Bottom Line
Although the engines are prone to subtle audible variations between full and partial-displacement use, it's barely noticeable. Honda, in fact, has equipped its benchmark van with noise-canceling technology, piped through the car's stereo, to effectively mask any evidence of the system.

Honda Odyssey
Power 255 hp, 250 lb.-ft. of torque, V6
Performance 060 in 8.6 sec., 117 mph top speed
Price $34,700 (touring version)

2.Hybrids
Tech
To stretch fuel economy, true gas/electric hybrids run either with both the gas engine and the electric motor working in a partnership of varying power ratios, or on electric power alone. "Mild hybrids," on the other hand, supplement gas engines with electric motors--adding horsepower without sacrificing fuel economy--but they can't run on electricity alone.

Pacesetter
Lexus RX 400h. Using parent company Toyota's technology, this true hybrid SUV combines a 3.3-liter gasoline V6 and a pair of electric motors. Its 268 hp and 212 pound-feet of torque thrust it to 60 mph in 7.3 seconds--half a second faster than its conventional sibling, the RX 330--while its fuel efficiency is a combined 29 mpg city/highway, a 38 percent improvement.

Other Options
The Honda Accord Hybrid gets a terrific boost from its electric motor, but test-drive it first--our sample vibrated slightly during engine shutdowns at stoplights.

Bottom Line
Most hybrid drivers are finding their real-world fuel economy to be lower than the Environmental Protection Agency estimates, which are based on outdated testing methods. Remember that hybrid efficiencies are greatest in urban driving--highway mileage is only slightly better.

Lexus RX 400h
Power 268 hp, 212 lb.-ft.of torque, combined V6 and electric motors
Performance 060 in 7.3 sec., 124 mph top speed
Price $49,200

3.Turbocharging
Tech
Using exhaust-driven fans--turbos--to compress air and force it into an engine generates a greater explosion inside the cylinder and, thus, more power. It's an easy, inexpensive way to goose both small and large engines' performance.

Pacesetter
Mitsubishi Lancer Evolution IX. For the ninth iteration of its hallowed Evo--a featherweight, all-wheel-drive sedan revered by rally fans and street racers--Mitsubishi squeezed another 10 hp out of the 2.0-liter inline four-cylinder engine, thanks largely to an innovative twin-scroll turbocharger that generates 20.1 psi of pressure inside the cylinders. The result is an astonishing 286 horsepower at 6,500 rpm, and 289 pound-feet of torque.

Other Options
The Porsche Cayenne Turbo's V8 gets a turbo boost from 340hp to 450 hp, making it the world's fastest SUV.

Bottom Line
For a performance car, natural aspiration remains the gold standard, because you have much faster and more linear engine response. But turbocharging is no slouch--turbo lag is mostly unnoticeable now, and manufacturers such as Audi, Porsche and Saab routinely turbocharge their lineups with impressive results.

Mitsubishi Lancer Evolution IX
Power 286 hp, 289 lb.-ft. of torque, inline 4-cylinder
Performance 060 in 4.4 sec., top speed unavailable
Price Not set at press time

4.Variable Valve Timing
Tech
Computer-controlled variable valve timing (VVT) smoothes out engine performance by optimizing the fuel and air mixture inside the cylinders at different engine speeds. Systems vary, but typically, at higher speeds, the intake valves open earlier, wider and for longer durations, delivering maximum fuel and air for increased power. At lower rpm, the overabundance of gas would be wasted and cause a rough idle, so the valves admit less.

Pacesetter
Ford Mustang GT. Its all-aluminum, 4.6-liter V8 employs a variable cam timing system that increases fuel efficiency, lowers exhaust emissions, and generates a robust power output of 300 hp and 320 lb.-ft. of torque.

Other Options
Most Hondas--the company that pioneered VVT--Toyotas and Nissans now feature VVT, as do many performance cars.

Bottom Line
This technology is a tremendous leap forward and is worth seeking out. Ford's version is one of the simplest yet, making it an affordable option for carmakers and, ultimately, more accessible to consumers.

Ford Mustang GT
Power 300 hp, 320 lb.-ft. of torque, V8
Performance 060 in 5.1 sec., 147 mph top speed
Price $25, 200

Horsepower Versus Torque
We all drool over horsepower figures, but what is often more relevant is torque--how much force the car applies to the road. Horsepower helps maintain speed (high-horsepower engines really strut their stuff at triple-digit speeds), but torque determines whether the car can accelerate with gut-churning ferocity. The Mercedes E500 and Acura RL both have 300hp, but the V8 Merc has 339 pound-feet of torque, and a 5.8-second 060 time, while the V6 RL musters only 260 lb.-ft. of torque and a 6.6-second 0--60.

NEXT: Handling the road | Braking and Traction

Table of Contents:
Power To Go Engines ........................| 1
Handling The Road Braking and Traction ........................| 2
Managing Power Transmissions ........................| 3
Information Access Driver Interfaces ........................| 4

HANDLING THE ROAD | BRAKING AND TRACTION

Air bags, seat belts and crumple zones may save your life in an accident, but better to avoid the need for them altogether. Antilock-brake system (ABS) technology has paved the way for new safety innovations that help you maintain control in cornering situations where conventional brakes would stop the wheels but not necessarily the car. The ABS wheel-speed sensor is a critical part of traction control, electronic stability-control and certain all-wheel-drive systems, all of which help your vehicle stay on its intended path.

All-Wheel-Drive Myths
All-wheel-drive systems are not panaceas for all driving conditions. The systems have limited, though important, usefulness. AWD is good in two situations: under acceleration in snow or mud, where it's priceless; and in high-performance driving, again under positive torque. Unless you drive very aggressively in slippery conditions, AWD doesn't help in the rain. When you back out of the throttle, it does nothing. It doesn't increase cornering limits or decrease braking distances. All-wheel-drive cars are safer, however, because they recover better in understeer situations and can take advantage of electronic stability control, since the speed of all four wheels can be computer-regulated via the brake, throttle or both.

1. Traction Control
Tech
Traction control uses the ABS sensors to determine when a wheel's rotational speed is out of sync with the engine's revs or the other wheels--when the wheel spins in wet or icy conditions or when accelerating--then selectively brakes the wheel and reduces power to it.

Pacesetter
Dodge Charger. The new, sub-$25,000 Charger demonstrates how traction control is now available across the price spectrum. The sharply styled sedan comes standard with a system developed by corporate cousin Mercedes-Benz.

Other Options
The Cadillac DTS puts 291 horsepower to the pavement through its front wheels. Traction control moderates power so that the driver isn't constantly muscling the front wheels straight.

Bottom Line
Some enthusiast drivers think traction control diminishes road feel and interferes with the car's performance. But no need to worry--manufacturers often include buttons to desensitize the systems.

Dodge Charger
Power 250hp, 250 lb.-ft. of torque, V6
Performance 060 in 6.0 sec., 130 mph top speed
Price $23,000

2. Multifunction Brakes
Tech
Disc brakes, which use hydraulic calipers to clamp down on rotors attached to the wheels, are quickly moving well beyond their now almost basic ABS systems.

Pacesetter
BMW 330i. The redesigned 3 Series includes several innovative brake features, among them Brake Standby, which anticipates hard braking and snugs the pads closer to the rotors, and Start-Off Assistant, which holds the brakes to prevent rollback when starting uphill from a complete stop.

Other Options
The Mercedes S-Class vehicles feature an electronic braking system, Sensotronic, that applies brake force to each wheel independently, helping retain control during panic stops, even on bumpy roads. Although it suffered early technical problems, the system has matured.

Bottom Line
At the very least, try to avoid any car that doesn't have antilock brakes--you can't afford not to have them.

BMW 330i
Power 255 hp, 220 lb.-ft. of torque, inline 6-cylinder
Performance 060 in 6.1 sec., 155 mph top speed
Price $37,000

3. All-Wheel Drive
Tech
If road conditions cause any of a car's wheels to slip, advanced AWD systems automatically divert power to the wheels that have grip. Working in concert with traction-control systems and limited-slip differentials, these systems shift torque front-to-rear and, in some cars, side-to-side to help maintain control.

Pacesetter
Infiniti M35. Unlike other AWD systems, Infiniti's version maintains a rearward bias for a satisfying rear-drive feel. In adverse conditions, though, it behaves like other systems.

Other Options
The German manufacturers have been pushing all-wheel drive for a long time. Most Mercedes and Audis offer it, and Porsche's 911 Carrera 4 makes excellent use of it as a performance enhancement.

Bottom Line
In general, the systems add weight and cost, and they probably aren't necessary for moderately powered cars driven in states that don't see much snow.

Infiniti M35
Power 280 hp, 270 lb.-ft. of torque, V6
Performance 060 in 6.0 sec., top speed not available
Price $42,600

4. Electronic Stability systems
Tech
Electronic stability systems moderate engine power and selectively apply brakes to individual wheels to stop cars from sliding out of control. Sensors compare wheel speed and steering angle to the vehicle's rotation around its vertical axis to determine whether the car is moving in the direction the driver intends.

Pacesetter
Porsche Boxster. The stellar Porsche Stability Management system counters wheel slippage prompted by drivers who lift the throttle abruptly during cornering--which can cause the back end to slide out--by subtly applying the gas to prevent a slide or spin.

Other Options
The Mini Cooper S Works comes standard with electronic stability control. This 201hp, 2,678-pound car would be prone to spins during aggressive driving if the system weren't in place.

Bottom Line
These systems don't differ much--except in how they're calibrated--so you can be happy just knowing your car has it.

Porsche Boxster
Power 240 hp, 199 lb.-ft. of torque, flat-6
Performance 060 in 6.2 sec., 159 mph top speed
Price $43,800

NEXT: Managing Power | Transmissions

Table of Contents:
Power To Go Engines ........................| 1
Handling The Road Braking and Traction ........................| 2
Managing Power Transmissions ........................| 3
Information Access Driver Interfaces ........................| 4

MANAGING POWER | TRANSMISSION

The manual transmission as we know it--a shifter on the floor and a clutch pedal--is suffering through its death throes. Its competitors? New seven-speed automatics, which improve acceleration over more sluggish versions and adjust shift points to maximize performance; continuously variable transmissions that enhance the power of small engines; and semi-automatic systems that offer the thrill and control of manuals with the ease, when needed, of fully automatic operation.

Read in-depth car reviews and learn the truth about buying wheels and tires, choosing gasoline, and getting your oil changed at www.popsci.com/autobuyersguide. Also: killer off-roaders (1), high-torque diesels"(2), new small convertibles"(3) and in-car entertainment systems (4).

Sequential Manuals
Tech
Standard equipment in Formula One cars because of their superhuman shift speeds, sequential manual transmissions--which use paddle shifters and an electrohydraulically controlled clutch (no foot pedal)--are now appearing in road-going performance cars.

Pacesetter
BMW M3. BMW offers its Sequential Manual Gearbox on its M3 for lightning-quick engagement of its six gears, with several selectable shift programs that allow you to change its demeanor--from easygoing to race-ready.

Other Options
True sequential manuals are few and far between outside the realm of supercars. The one in the new, $200,000 Ferrari F430 is, well, recommended.

Bottom Line
Don't mistake a manumatic for a sequential manual. Those allow you to shift an automatic transmission at will; an SMG is a manual at heart, complete with robust cogs and a clutch instead of the torque converters and planetary gears found in automatics. These truly are the future of performance driving.

BMW M3
Power 333 hp, 262 lb.-ft. of torque, inline-6 cylinder
Performance 060 in 4.8 sec., 155 mph top speed
Price $50,400

Continuously Variable Transmission
Tech
A continuously variable transmission (CVT) uses a moving pulley system and a belt or chain to infinitely adjust the gear ratio across a wide range and transfer power between the engine and the wheels.

Pacesetter
Ford Freestyle. The CVT helps make the most of the Freestyle's modest 203 horsepower at all speeds and loads and deliver a respectable combined 22 mpg.

Other Options
Most hybrids, including the Lexus RX 400h and the Ford Escape Hybrid, use CVTs because their gasoline-engine components are generally smaller than they would be in nonhybrid cars of the same size, making the CVT's ability to keep an engine in its sweet spot particularly useful.

Bottom Line
CVTs can't yet handle the high torque demands of perfomance cars. Some people are put off by the incessant waaaaa of a CVT that remains at a constant rpm during acceleration and doesn't give the aural cues they're used to as the car increases speed.

Ford Freestyle
Power 203 hp, 207 lb.-ft. of torque, V6
Performance 060 in 8.2 sec., 111 mph top speed
Price $27,500

Automatics
Tech
Automatic transmissions adjust gear ratios as the car speeds up, so the engine can work at the optimum speed for the task at hand--high revs for power and acceleration, low revs for economy. Better automatics have more gears and adaptive shift maps that adjust based on whether you're driving vigorously or just cruising around.

Pacesetter
Mercedes E350. Mercedes's 7G-Tronic seven-speed automatic helps improve acceleration by adding shift points--via the additional gears--to give more precise control over how power is applied.

Other Options
The Range Rover Sport's transmission is calibrated for both off-road and sporty on-road driving--for example, it won't upshift if the car is being driven hard through corners.

Bottom Line
Ultimately, more gears are better. Each new gear helps to more efficiently put power to the pavement, providing more precise control over the relation between the vehicle speed and the engine speed.

Mercedes E350
Power 268 hp, 258 lb.-ft. of torque, V6
Performance 060 in 6.5 sec., 130 mph top speed
Price $50,800

Dual Clutch
Tech
A variation on the sequential manual gearbox, this technology--currently
available only on Audi and Volkswagen production cars--uses a pair of clutches to cycle through gears, prompted by the computer or the driver, via steering-wheel-mounted paddle shifters. Each gear change takes just two tenths of a second, with no interruption of the torque flow.

Pacesetter
Audi A3. The Direct-Shift Gearbox (DSG) is standard in the forthcoming V6 version of the A3 Quattro--a testament to the new technology's excellent performance.

Other Options
The DSG transmission is also available in Audi's sports car, the TT, and the Volkswagen Beetle turbo diesel.

Bottom Line
On the road, the DSG shifts noticeably faster and more smoothly than conventional automatics, making for much more spirited driving. If high-speed shifting isn't appealing, you can order the 2.0-liter A3 with a conventional stick shift.

Audi A3
Power 200 hp, 207 lb.-ft. of torque, inline 4 cylinder
Performance 060 in 6.7 sec., 130 mph top speed
Price $25,460

NEXT: Information Access | Driver Interfaces

Table of Contents:
Power To Go Engines ........................| 1
Handling The Road Braking and Traction ........................| 2
Managing Power Transmissions ........................| 3
Information Access Driver Interfaces ........................| 4

INFORMATION ACCESS | DRIVER INTERFACES

Conveying information to the driver efficiently and without distraction is, evidently, an extreme challenge for automobile manufacturers. They've all struggled with everything from logically organizing instrument displays and controls to making functions on the new LCDs easily accessible. The systems have improved substantially, and manufacturers now offer navigation, entertainment and vehicle-systems controls that are intuitive and easily navigable.

Audi A6
Power 335 hp, 310 lb.-ft. of torque, V8
Performance 060 in 6.0 sec., 130 mph top speed
Price $52,220

Vehicle-Systems Interface
Tech
Screen-based interfaces allow drivers to control audio and navigation functions, climate, and even suspension settings.

Pacesetter
Audi A6. Audi has mastered this art. The elegant Multi Media Interface allows the driver to oversee vehicle systems without a dizzying array of buttons or a maddening hierarchy of menus and submenus. A second, smaller information screen sits between the speedometer and the tachometer for easy reference while driving.

Other Options
Many Japanese systems, such as those found in the luxury Lexus and Acura lines, are almost as good as the Audi's, but the American manufacturers often have unwieldy, unintuitive systems that are more distraction than true driver aid.

Bottom Line
The best displays are high up, near the driver's line of sight, with controls positioned between the two front seats. Steer clear of poorly laid-out radio controls. Fortunately, many controls are migrating to the steering wheel, where they should be.

Function-Specific Systems

Off-Road Information Screen Stuck in a rut? If you don't know what your wheels are doing, it can be awfully hard to get out. The Land Rover LR3's color touchscreen tells you, among other things, the steering angle, whether a wheel is off the ground, and how the differentials are set.$50,000

Head-Up Display It's fighter-jet technology for the street. The head-up display for the Chevrolet Corvette, a 186mph hot rod, features a floating field of data, projected on the windshield just above the dashboard, that might otherwise draw eyes from the road. It includes speed, revs, fuel level, even cornering forces. $48,900

Hybrid Management Screen Drivers can maximize the efficiency of their hybrids by adjusting their driving style. The Ford Escape Hybrid has an LCD with a real-time power path offering graphic indicators of fuel consumption, battery charge levels, and how the motors are working together. $28,600