A&Q about 350Z
Q:
YES! Had the EXACT same problem! Took it to the dealer and they replaced the "gauge cluster computer" and it cured it. Took a day to do. They won't let you drive it until it's fixed because the speedo doesn't work.
So rest assured, it's not too strange and is a relatively easy fix...
Only problem was for me, the idiot technician didn't re-assemble everything correctly and *broke* the gauge nacelle... then I had to leave it at the dealer AGAIN when I discovered it was falling apart for THREE WEEKS while they ordered a new gauage cluster assembly. Fortunately, they gave me a rental.
A:
I had the same thing happen to me. Everything went to zero right after start up. I turned the ignition off and back on and everything was working fine then. It took a while for the m.p.g. average to come back on-line though. It has been working fine ever since.