Roadster is all about crazy range and acceleration.
To make it really go to 4000 kph crazy quickly, of those 3 motors probably none can be anything other than a big fat induction unit such as seen in Model S/X, probably even the extra bulky and lossy Performance version.
To stick one PMSR motor in there, such as the S and X now receive, acceleration will be someone restricted at higher speeds as the slip limit for 211 kW is not all that fast, even on the front wheels.
It's a trade-off, though. More efficient motors will save good weight while still achieving targeted range.
In Model S/X, the motors and new inverter probably added around 6% in range for the non-P versions such as could have been the lone front motor, the other 2% coming from min/max voltage changes, bearings, HV cabling, etc. Let'say 1000km is the target and they never considered to PMSR motors, but now WOULD, then in stead of the previously necessary 200 kW with all-Performance motors, they could suffice with 188 kW. 12 kWh in cells weighs 48 kg and then there are some connectors and fuses. Say, 60 kg to be saved. On top of the ~20 kg in the motor itself, so 80 kg. That 80 kg is ~4% of the car. Losing (round number, no clue what it might be) 50 kW or so by taking a lighter front motor would drop peak power from 1,000 kW to 950 kW, some 5%. So it actually might all work out.
But then, we have to be real here. When tesla came out with the number, which is after they put the first Roadster prototypes together, they really knew all about the tech that's not being implemented in S/X.
200 kWh to achieve 1,000 km EPA never was really impressive for a smaller car. Old Roadster was way more efficient than Model S, but New Roadster would be way lossy. This would be partially explained by the 4x bigger battery adding weight and then completely by having only super lossy Performance induction units to choose from.
But say they make a slightly slower version, 3x that PMSR motor with some clever clutches to allow some to be turned off. Smaller battery, say 120 kWh. That all would save good weight, 400-500kg or so. 633 kW in a lighter car, that is going to be bonkers still. I can see around 2 seconds to 60 mph still be possible. Heck, even 400 kph max is still possible with that sort of power although there may not be a gearing that allows for both the top speed and the low speed torque needed.
A car lighter and lower than a Model 3, using the same motor but in the front, should achieve a lower consumption figure. In stead of 150 Wh/km, let's go for 140 Wh/km which is quite conservative. With 112 kWh usable, that would make for 800 km of range on the EPA cycle. Not too shabby, huh?
Tester report that even the 3PD lack a bit of the punch of an SP100DL and that that's due to the motor being a different technology. But if you roughly double that power and reduce the weight, I'm sure all will be fine :-D
Now putting that 800km 120 kWh Light Roadster on the track...
We know these PMSR motors are quite able to deal with continued pushing, much better than the motors in P100DL cars.
With a car lighter than the 3PD, having double the power to the road and even less heating issues (better inverters), wider tires, track focused suspension, 400-500 kg lighter than the Big Roadster, it may well track (much) faster.
Now, Tesla is not in the business of making the best car they can. They focus on making cars the way they like them. All but completely ignoring knowledge and trends in the market. So I don't think they'll make a Roadster with 3 (let alone 4) of their cheapest most efficient motors. 4 motors is well established as the best way to get track performance, but they feel they've done enough showing a working prototype that felt really quick to those who got a 0-60 ride in it.
Tesla barely cares about on track performance. Proven by Randy Pobst's involvement actually delaying Track Mode. They were going to launch it as he got to test it and then it turned out to not be all that great. That's right, they were to roll out Track Mode without due diligence asking a pro driver. And then he got only a few hour with the engineers, on track. Then it was released to cars.
An ambitious hacker/mechanic may well be able to shed that 400-500kg off the Roadster they'll sell, and make it work efficiently without any Tesla assistance. Lap it faster than the original thing, while getting better economy and 800 km of range to boot. But Tesla won't care. I hope they prove me wrong and FOR ONCE go for a best effort. Not just a one trick pony that goes quick straight on while dumping a godawful amount of waste onto the environment to get a silly 3-figure range whatever the economy. But in stead of saving the world, they are more likely to actually try and stick cold thrusters into the back seat to make the (needlessly heavy) 200 kWh actually fly for a few seconds. And I do believe it could be done. But imagine they make the lighter version first and stuck the thrusters into that one. How that would play out for 3D thrust performance boost...