MOTORSPORT: Daytona Porsche's possum passenger

International television viewers get a kick out of seeing a kangaroo hopping along the Mt Panorama circuit at Bathurst or a rabbit scooting across the track at Phillip Island.

But when veteran American racer Andy Lally felt a thud at 5am Sunday during the Daytona 24-Hour it was a possum that had hit the Porsche 911 he was driving.

Lally thought it may have been debris from another of the 53 cars that started the race.

It was four hours later that he discovered the truth, when the dead possum was found in the bloodied boot – or what Americans call the trunk – at the front of the rear-engined Porsche.

One of Lally's three co-drivers, German Marco Seefried, later tweeted: "Finally found out what Andy hit last night. We had a passenger on board."

The contact between the marsupial and the Magnus Racing Porsche 911 GT America had broken the car's splitter, bent but didn't break the Australian-made PWR radiator and pierced the "tub".

A possum had been spotted pre-race nestled beside the top safety wall of the banking of the Daytona International Speedway that forms part of the circuit for the 24-Hour.

"Mike V5" later tweeted a photo of that possum there, although it's not certain it was the nocturnal one that hours later came to be nicknamed "Ballast of Possum" or BoP – an acronym that in American sports car racing parlance stands for a balance-of-performance adjustment in the race rules.

The posthumous "Ballast" even had its own Twitter handle and a hashtag,  #AvengeBallast.

At one point Magnus Racing, class winner at the Daytona 24-Hour three years ago, thought its Porsche was out of this year's twice-round-the-clock classic, more a race of attrition than ever, with an oil leak.

But the crew got the car back on the track and it was classified a finisher.

Lally, a 39-year-old New Yorker and staunch animal activist, was saddened by the possum's fate but felt compelled to tell the story of what had happened as social media went crazy over the incident.

Here are Lally's tweets over several hours during his time out of the Porsche.

"Smoke. Crew is trying to figure out what it is. Temps are fine."

"I'm about to tweet something gross. But I can't not. At 5am I reported hitting debris on the banking. We never found it. Till just now ..."

"This [picture of possum] broke through the splitter & tub and then into the front of the car. By the way we are out of the race."

"HUGE testament to the PWR radiators. BENT it, and still held water."

"Crew is fixing the car. They've posthumously named the possum 'Ballast'. Sad, but I think we should put him back in to take the checker [chequered flag]."

"Crew fixed it! Back on track! Thank you crew!"

"Looking at scoring. Hard to believe that more than 20 other cars had a day worse than ours. Most attrition I've seen at Daytona since 2001."

"Climbing in to try and take it to the checker."

The No. 44 Porsche indeed took the chequered flag – in 29th place outright, albeit 124 laps behind the victorious Riley-Ford Daytona Prototype that did 740 laps of the 5.7km circuit, but 11th among the GT Daytona cars, two places and 23 laps ahead of the Aston Martin Vantage co-driven by Australian James Davison in the same category.

And on Twitter, "nascarcasm" – who had followed the possum tale throughout – tweeted: "Rest peacefully, Ballast, our furry marsupial compatriot. Your death was not in vain."