Upper range of speedometer numbers is a marketing tool -- and one big tease

Dear Tom and Ray:

My 9-year-old son asked me why the speedometer on cars indicate speeds much higher than legal driving speeds. If it is illegal to drive 100 mph (or faster), then why indicate that the car can travel that fast in the first place, not to mention the fact that most cars can't reach these speeds in the first place? I didn't know the answer, so I thought I'd ask a car company. Toyota wrote back with:

Thank you for contacting Toyota Motor Sales, U.S.A., Inc. We appreciate this opportunity to address your inquiry. Some states within the United States have higher speed limits than other states. We hope you will find this information helpful. Thank you for taking the time to contact us with your inquiry.
Sincerely,
Toyota Customer Experience

Which was a stupid response.

Nissan wrote:

Thank you for taking the time to contact Nissan North America, Inc. and allowing us the opportunity to read and respond to your e-mail inquiry.
All vehicles are designed in this fashion, regardless of make or model. If you are seeking an exact reason as to why vehicles are designed this way, no further information can be provided.
I apologize if the response given is not satisfactory. Unfortunately no further information regarding vehicle/speedometer designs can be offered.
Sincerely,
Nissan North America, Inc.

An equally dismal response. GM and Ford did not respond at all. Can you help answer this question?
-- Robert

Tom: Hang on a second, Robert. I'm just taking some notes. I think we can use some of those response lines in future columns.

Ray: The answer is marketing, Robert. Most of us drive our cars between zero and 80 miles per hour. But by placing a 140-mph speedometer right in front of your face, the manufacturer is suggesting to you that you could go a lot faster.

Tom: Right. It suggests you're showing admirable restraint by holding this "crouching tiger" to the speed limit.

Ray: That's an appealing characteristic for most people -- to have way more power than you need.

Tom: It's like the ads that show SUVs climbing up the sides of city buildings, or blasting through eight feet of snow at 60 mph. Ninety-nine percent of people use their SUVs to commute to the office and back. But the image of being able to break out of your mundane life is what sells these vehicles. A 140-mph speedometer works the same way.

Ray: It's like my bathroom scale. I may use only 160, but it's good to know I can go up to 350 if I need to!

Tom: I mean, there are some pseudo-practical reasons for doing this. If a manufacturer makes some cars that go faster than others, it's easier and cheaper to make one speedometer for all their cars. But the top speeds on speedometers are still higher than any of the cars can go, and far higher than anyone is allowed to go.

Ray: So we have to conclude it's a sales tactic, Robert. I apologize if the response given is not satisfactory. Unfortunately no further information can be offered.

(Car Talk is a nationally syndicated column by automotive experts (and brothers) Tom and Ray Magliozzi. Write to them at the Car Talk Web site.)