Renger van der Zande has admitted that multi-class racing is tricky at the moment due to slow cornering speeds in slow-speed corners for the top class GTP cars.
"In general, GTPs have been very slow in slow-speed corners; as fast as GT cars," he said.
"Only the high-speed corners where we can make a difference compared to the GT cars, so it’s not been too easy to overtake. We go to tracks where there are maybe two or three corners and the straight where you can overtake, where with the DPi you could overtake in any corner.
"If you talk about the dynamics of multi-class racing, it’s not so easy right now. Also, we’re heavy and we have to break quite early compared to the GT cars who have ABS.
"Sometimes you outbrake them on the inside and they can still brake later than us, so it’s only a couple of spots on the track where you can overtake normally."
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The GTPs were introduced last year as the replacement for the former top class in the IMSA Sportscar Championship, the DPi class.
Every GTP car in IMSA right now uses the LMDh technical regulations, which state that the car's minimum weight must not be below 1030kg. And that's without Balance of Performance to balance the cars out, which can add at least another 10kg at times.
Compare this to the DPi minimum weights, which were around 100kg lighter — roughly a tenth of a GTP's total weight — and you can start to see the problem.
This weight has come from a variety of places, but the main culprit is the hybrid element, which is compulsory in the rules. This includes the hybrid motor, situated on the rear axle to drive power to the rear wheels, and the battery, which adds a substantial amount of weight to the car.
However, at Laguna Seca, van der Zande isn't expecting the same problems with lapping slower class traffic.
"It looks like we’ll be quite a bit faster than the GT cars at Laguna Seca compared to the other tracks," said the South African.
"From that perspective it’s easier to overtake them. Your cornering speed is higher where you can probably have more corners where you can overtake.
"I think Laguna Seca with the higher grip, and we have a bit more downforce the car, will probably have more overtaking opportunities with the GT cars this time.”
The higher grip van der Zande mentions isn't just Cadillac, and their rivals Porsche, Acura and BMW, understanding how to extract more downforce from the cars. It's also to do with the repaved track surface, as the South African's teammate Sebastien Bourdais explains.
“We did come and test with both Cadillacs, both BMWs and both Penske Porsches, so we did have time to experiment and try quite a few things," said the veteran Frenchman.
"Grip has gone up a lot. It’s probably going to be at least a couple of seconds faster and it’s always an awesome feeling when you drive on a repaved track.
"I’ve always enjoyed Laguna, but tire degradation was high and grip was quite low at the end of the cycle of the old pavement. So, now it’s full force, maximum attack and commitment, so it’s a ton of fun to muscle those GTPs around. You should see some pretty incredible speeds around the weekend.”
Van der Zande added: "The Monday after our race last year they started to work on the track ,and we saw IndyCars flying off because there was only one line that was grippy, and anything that was off line was not good.
"When we were testing there that improved a lot. There was grip everywhere. It’s just the speeds are so much higher that if you have a little off you’re flying off a lot faster. I think you’re going to see if people go off it’s easier to end up in the barrier, which makes it tricky and you can feel that from the car."
The IMSA Laguna Seca round takes place this coming weekend, beginning on Sunday 12th May at 12:10 local time.