Among adults whose household owns a vehicle, 73 percent had personalized their principal vehicle in some way or plan to do so; this cuts across all major demographic segments.

Consumer Reports

Overall, this study found that these automotive enthusiasts have spent an average amount of $711 per car. Extrapolated out to the total population aged 18-64, consumers have spent an estimated $81 billion on the vehicles they currently drive. Based on the average reported six-year ownership period, this breaks down to $13.5 billion, or $118 per person, spent annually.

Leading reasons why a car owner invests in aftermarket products:
To better fit my lifestyle 48%
To enhance comfort 44
To add features not available from the factory 37
To improve safety 36
To improve appearance 36
To improve performance 34

For this study, personalization was defined as any modification from the new or used vehicle's original condition, made or planned after sale by the owner. The most common upgrade was floor mats but the enhancements ranged all the way to extreme performance.

To learn what Americans buy for their cars, and why, the Consumer Reports National Research Center conducted a random, nationwide telephone survey from Oct. 12-15, 2006, of 855 adults 18 and older whose household owns at least one vehicle.

THE PARTS LIST

The most common modifications made to or intended for new and used cars:
Floor mats 49%
Stereo system 28
Car alarm 22
Window tinting 22
Speakers 22
Steering wheel cover 18
Performance tires 17
Seat covers 17

WHO IS THE MODERN CAR ENTHUSIAST?

Truly an equal-opportunity indulgence, both sexes proved to be engaged in car personalizing, with 77 percent of men and 70 percent of women participating in the car customizing tradition.

Despite the fact that today's youth is coached on car modifying from movies ("The Fast and the Furious Tokyo Drift"), television ("Pimp My Ride," "Overhaulin'"), and video games ("Midnight Club," "Need for Speed"), age groups also defied stereotypes in this study. As expected, the 18-34-year olds were the most active group—78 percent enhanced their ride. But 35- to 54-year-olds followed at 74 percent, and the 55-and-over crowd is involved at 68 percent.

A COMFORTABLE INTERIOR

Most aftermarket modifications were done to the interior, with 61 percent of respondents who own a car making the cabin more comfortable and conducive to their mobile lifestyle. Floor mats lead the changes at 49 percent. An easy install item, floor mats are not standard on all cars and may be less expensive when bought outside a dealership. Plus, embroidered floor mats can add character while deep, rubber mats can protect against mud and snow.

Other low-cost, low-effort upgrades include steering wheel cover (18 percent), seat covers (17 percent), shift knob (5 percent), and dash appliqués (4 percent).

PLUGGED IN—ELECTRONICS

Half the car owners plan to change, or have changed, in-car electronics, with stereo systems heading the list at 28 percent, despite the trend in factory-supplied units sounding better and being increasingly difficult to replace. At 22 percent, car alarms and speakers are also common. Satellite radio units logged in at 13 percent—a relatively strong return considering that many new car models offer Sirius or XM systems as standard or optional features. Hands-free cell-phone setups also came in at 13 percent. Consumers also looked to high-tech luxuries, such as video systems (10 percent) and navigation systems (9 percent).

LOOKING GOOD—EXTERIOR

A third of consumers pursued the exterior modifications in some way, led by performance headlights or fog lights (11 percent).

Three-quarters of pickup truck owners surveyed have installed, or plan to install, a bedliner. This is a significant figure considering some models, such as the Chevrolet Avalanche and Honda Ridgeline, come with bedliners.

Other modifications were less common and split between cosmetic and functional. At 7 percent, spoilers were next in the ranking order, trailed by roof/bike racks (6 percent), brush guards (6 percent), and pin stripes or other body art (5 percent).

THE NEED FOR SPEED-—PERFORMANCE

The most common powertrain upgrades focused on improved engine breathing, with a performance air filter or intake leading at 17 percent, and performance exhaust or muffler at 11 percent. Fuel-saving devices came in at 10 percent, despite the fact that Consumer Reports testing has yet to identify an add-on that could increase mileage. (See "Gas-saving devices tested" on ConsumerReports.org.)

One in 20 drivers—five percent—have made or intend to make a significant performance commitment by adding a turbocharger or supercharger—(devices that force air into the engine to generate more horsepower). With similar popularity, enthusiasts installed performance computer chips (6 percent) and new pulleys (4 percent). Those aftermarket pieces can enhance performance at the expense of fuel economy and clean emissions.

Chassis modifications are made by, or planned by, one-third of personalizers, led by one of the most-effective component upgrades: performance tires (17 percent). Aftermarket wheels followed at 12 percent.

PARTS SHOPPING

Half of consumers purchase their aftermarket parts and accessories at their local auto parts store. Overall, online purchases were made by 26 percent of consumers, broken down by aftermarket parts manufacturer (14 percent), general auto parts Web site (14 percent), and from the auto manufacturer (11 percent). Major retailers, such as Sears and Wal-Mart, are used by 34 percent of drivers overall. Used-car owners more strongly favor local parts stores (57 percent) and major retailers (39 percent).

More than a quarter of the respondents had modifications performed where they bought the components, while 25 percent hired a mechanic. This line of questioning revealed clear gender lines, with 32 percent of men saying they do their own work, compared with 5 percent of the women. On the other hand, 20 percent of women said another family member does the work, vs. 4 percent of the men making the same statement.

THE FINISH LINE

At the time of our survey, fewer than one in five consumers expected to continue personalizing, led by young men and drivers in the Western and Southern regions. The planned modifications were expected to reach a mean of $1,190; a high 45 percent of modifiers expect to spend at least $1,000 above their previous expenditures. While not all intentions will translate to purchases, it is clear that customizing is an enticing pursuit.

Why not continue personalizing?
Car is considered complete 82%
Budget concerns 25
Plan on selling the vehicle 23
Concerned about resale value 20

Personalizing cars is a long-standing American tradition that continues today, with most adult car owners personalizing their vehicle in some way. While modifications may run from mild to wild, car owners on average invest hundreds of dollars adding comfort, convenience, and style to their rides.

A new or used car represents a significant purchase, and it is natural to want to heighten the driving enjoyment. Consumer Reports encourages auto enthusiasts to fully research and consider the potential compromises of modifications and local legal issues before investing in the parts and labor. (See "The pros and cons of modifying your car" on ConsumerReports.org.) Making a car too distinctly your own might make it harder to find a buyer or get top dollar when it comes time to sell. And many so-called performance modifications carry potential compromises of ride quality, handling, braking distance, and fuel economy.

For more information on the latest car customizing products and trends, see Consumer Reports coverage of the annual Specialty Equipment Market Association (SEMA) aftermarket event.

The full Ratings and recommendations for more than 200 vehicles, along with the latest information on thousands of other products and services, are available to ConsumerReports.org subscribers. Find out how to subscribe today.