With a little under an hour left on the clock in the 10-hour WeatherTech SportsCar Championship curtain-closer at Petit Le Mans, the two CGR-run Cadillac DPi-V.Rs came to blows at Turn 1 as they disputed third place.
Bamber had been running ahead in the #02 car he shares with Alex Lynn and Ryan Hunter-Reay, but was baulked by a Mercedes GTD car, giving the #01 machine of van der Zande a run on the outside.
But as the Dutch driver tried to turn in to make the corner, he made contact with Bamber on the inside, sending both cars off-course and into the barriers - and effectively ending any hopes of a final win for Cadillac in the DPi era.
Van der Zande, who was sharing a cockpit with Sebastien Bourdais and Scott Dixon, struck an apologetic tone when looking back on the incident.
"We came to Petit Le Mans to win and to finish the race like this is really difficult," said van der Zande, who is already confirmed to be part of Ganassi's 2023 IMSA effort with the all new Cadillac V-LMDh alongside Bourdais.
"There’s never any intention to come together out there and we’ll reflect on this and regroup as a team."
Bourdais added: "Obviously, that is not the end of the championship that anybody wanted for Cadillac Racing and the Chip Ganassi Racing team.
"It’s a shame; there was a race win on the line, and everybody wants to go out on the high note. We’re disappointed to finish like that with the new era ahead of us."
The #01 Cadillac was finally classified fourth, four laps down, after making it back on track following the incident, while the sister #02 car was eighth overall and fifth of the DPis, five laps back.
Bamber added: "I think we had a fantastic race all day and had a really good car with the No. 02 Cadillac. We managed to lead a lot of laps and hours and that’s something to be proud of.
"Obviously, I’m quite disappointed with what happened and mostly for everyone at Cadillac and Chip Ganassi Racing. We come here to win as a team, whether it’s the No. 01 or the No. 02, and that is a tough scenario to be in."
AXR gives Cadillac double podium on DPi farewell
While DPi rival Acura swept both the drivers' and manufacturers' championships thanks to victory for Meyer Shank Racing, trouble for the other ARX-05 of Wayne Taylor Racing allowed Cadillac to take the two remaining spots on the podium.
The #31 Whelen Engineering-branded Action Express Cadillac of Pipo Derani, Olivier Pla and Mike Conway was promoted to second, while Kamui Kobayashi brought home the #48 Ally Racing-branded car he shared with Jimmie Johnson and Mike Rockenfeller a lapped third.
"Ups and downs, but in the end we were there to fight for the win," reflected Derani. "Unfortunately, I got really unlucky with traffic at the last restart, so I lost a lot of time and then I was catching them back. But that’s part of multi-class racing.
"I’m glad we had a fantastic time with the DPi car. The Cadillac was amazing. Most of my wins and the championship have been with this car. A great era that comes to an end, but I’m glad I am here to be fighting for the win.”
