Chords used:

open G :                       G

Special D/F# with no high F# : D* 

e--0-- | 
B--3-- | 
G--2-- | 
D--0-- | 
A--0-- | 
E--2-- | 

open C :                       C

C/F# :                         C/F#

e--2-- | 
B--3-- | 
G--2-- | 
D--0-- | 
A--0-- | 
E--2-- | 

open Em :                      Em

open Am :                      Am

At the chorus Mark plays a little riff off of an open C chord with a 
changing base note:

e----------------------------- | 
B----------------------------- | 
G------0------0------0------0- | 
D----2------0------2------0--- | 
A--3------2------0------2----- | 
E----------------------------- | 

G      D *     C
You are a car
G      D *     C
You are a hospital
G              D *
I'd walk to hell and back
D/F#
To see you smile

C chorus riff
On saturday

G      D *   C
You are a star
G      D *           C
You are a sea of air
G               D *   
I play great keyboards
D/F#
Of horses' teeth

C chorus riff
On saturday
On saturday

G       D *                  C
            I'd like to tell you
         Em        D/F#                 Am
How I feel
                   D/F#
I'll probably keep it
           C chorus riff
'til saturday
Oh saturday, saturday
Oh saturday, saturday
Oh saturday, saturday
Oh saturday, saturday
Oh saturday, saturday