lbrandt

Did some searching and couldn't find an answer, but on my speedometer mph are white and kph are red EXCEPT for the 55 mph tick mark which is red instead of white...just wondering why this is..optimal mpg? torque? What are your thoughts?

1987 5000S Quattro

audi-bahston

I'm guessing here but 55 MPH was pretty much the universal speed limit back then

MrGoodbytes

Even new cars today should have the 55mph marked.

Kneale Brownson

The Double Nickel speed limit law was adopted in 1974 after President Nixon made the initial administrative rule limiting vehicle speeds to 55 mph the year before, I believe, to help with the fuel shortages in the 70s. The law made his rule permanent until adjustments were made in more recent years. The presidential rule applied to any states accepting federal highway funds, as did the law. Carmakers began indicating the 55 not too long after.

lbrandt

Thanks for the answer.

Yeah, I'm a little green :-)

Anyone know what speed then is considered MOST mpg efficient for the 2.3L audi (or maybe a way to calculate the optimum mph for mpg?)

MrGoodbytes

Low rpms, low throttle position, high gear.

Pushbutton_auto

It will cruise all day, for about 25-30 mpg.

but if open her up, esp d turbo, you can see the needle go down.

greenaudi100german

I think I get about 27-28 mpg on my 100 automatic going 55. I keep the tires inflated at about 42 psi also. Going 70mph I get about 23-24mpg. I've done some experimentation with this. This is all with the air conditioner off.

lbrandt

42 PSI on the tires? Isn't that like 10 psi higher than recommended?