Crossing the Hay Plains one night on the way to Adelaide for the F1 race, in an XF Fairmont Ghia. Two of us asleep, a mate driving. Woken by the car suddenly moving all over the road, he'd hit an echidna and the front tyre blew out like it was a bomb - and he was probably clocking $1.60 or so at the time. Luckily he is a bit of a gun behind the wheel and stopped the car safely. Also lucky that we were in the XF and not the Brock Director we usually took over, which was happy at $2.00+ across the plains...
Front tyre destroyed, rear tyre with a dozen or so quills in it but holding air. Small steaming red patch on the tar where the echidna departed this life (we went back to look).
Two new tyres later that morning in Mildura, been wary of echidnas ever since!