I think this is it:

Southbound On The Freeway

A tourist came in from Orbitville, parked in the air, and said:

The creatures of this star are made of metal and glass.

Through the transparent parts you can see their guts.

Their feet are round and roll on diagrams of long

measuring tapes, dark with white lines.

They have four eyes. The two in back are red.

Sometimes you can see a five-eyed one, with a red eye turning

on the top of his head. He must be special--

the others respect him and go slow

when he passes, winding among them from behind.

They all hiss as they glide, like inches, down the marked

tapes. Those soft shapes, shadowy inside

the hard bodies--are they their guts or their brains?

By May Swenson

Dunning, S., Lueders, E., Smith, H. (1996). Reflections on a Gift of Watermelon Pickle...And Other Modern Verse. NJ: Scott, Foresman and Company, p. 82.

I think this is it:

Southbound On The Freeway

A tourist came in from Orbitville, parked in the air, and said:
The creatures of this star are made of metal and glass.
Through the transparent parts you can see their guts.
Their feet are round and roll on diagrams of long
measuring tapes, dark with white lines.
They have four eyes. The two in back are red.
Sometimes you can see a five-eyed one, with a red eye turning
on the top of his head. He must be special--
the others respect him and go slow
when he passes, winding among them from behind.
They all hiss as they glide, like inches, down the marked
tapes. Those soft shapes, shadowy inside
the hard bodies--are they their guts or their brains?

By May Swenson

Dunning, S., Lueders, E., Smith, H. (1996). Reflections on a Gift of Watermelon Pickle...And Other Modern Verse. NJ: Scott, Foresman and Company, p. 82.

http://www.u.arizona.edu/~pforeman/Southbound-5-3.html

I think this is it, sorry I couldn't copy and paste the poem.

I think this is it:

Southbound On The Freeway

A tourist came in from Orbitville, parked in the air, and said:

The creatures of this star are made of metal and glass.

Through the transparent parts you can see their guts.

Their feet are round and roll on diagrams of long

measuring tapes, dark with white lines.

They have four eyes. The two in back are red.

Sometimes you can see a five-eyed one, with a red eye turning

on the top of his head. He must be special--

the others respect him and go slow

when he passes, winding among them from behind.

They all hiss as they glide, like inches, down the marked

tapes. Those soft shapes, shadowy inside

the hard bodies--are they their guts or their brains?

By May Swenson

Dunning, S., Lueders, E., Smith, H. (1996). Reflections on a Gift of Watermelon Pickle...And Other Modern Verse. NJ: Scott, Foresman and Company, p. 82.