@bpon89 Which MPP kit do you have, Comfort or Sport?
Exactly which Model S was the loaner, and when was it built or at least which model year? (Model S suspension tuning has changed a lot over the years.)
A few thoughts (and questions) as a longtime Model S P85 with air suspension owner (and I've driven many other Model S over the years):
- What size tires did your Model S loaner have? E.g. if it had 245/45 (that would be 19" on a Model S) and your M3P is on 235/35, that's a SIGNIFICANT sidewall difference. That makes a big difference in how stuff like railroad crossings feel.
- I say this with lots of experience - my S P85 came with 245/35R21 and I later switched it to 245/45R19. My M3P came with 235/35R20 and I switched it to 245/45R18.
- If you're actually bottoming out, then setting your dampers firmer and/or raising the car could help.
- How smooth or rough is this railroad crossing? Is it well maintained or a real nasty abandoned one?
- For really rough stuff I find that firmer suspension tuning - meaning springs and damping both - rides better than a softly tuned suspension which just bottoms out or loses control more easily.
- Most Model S have air suspension. This gives a certain muted, insulated quality to the ride that I've never experienced from any coil suspension. Model S with factory coil suspension completely lacked this...I think it's an air suspension thing.
- The 100D / P100D era (maybe 90D / P90D too, I forget) had very soft suspension tuning. Great for a smooth ride driving straight. However with the extra soft suspension, bigger heavier batteries, and extra motor up front (compared to my P85) these cars became wallowing boats or tanks in the turns. There was a real handling tradeoff for this level of smoothness.
- Earlier Model S suspension tuning varied wildly, e.g. P85+ and early P85D were nicely sporty and firm (by big car standards - still no Model 3), while the original Model S like my P85 was pretty soft (but not as heavy or wallowy as the P100D).
- Raven and Palladium have active adjustable dampers in addition to the air springs. I don't have much experience with these, but I would certainly expect a smoother ride than a Model 3 lowered on coilovers!
When I compare my S P85 on air springs to my M3P on Redwood Performance Sport coilovers, both on 245/45 tires, with Redwood Ohlins dampers set halfway in their adjustment range (16 of 32 clicks from full stiff), the Model S is smoother when driving slow and casual over straight city streets, but the harder and faster I drive, the smoother my M3P becomes in comparison - it's smoother (and handles worlds better) when driving very fast over a rural back road. My wife even called it "smoother than the [Model S]" after her first long drive on the coilovers with 40+ miles of twisty rural road (where I'm pretty sure she drove fast - I wasn't with her for the drive).
On the highway both cars ride just fine in my opinion. Can't think of anything to complain about with either. Same for more casual, sane driving pace on those twisty rural roads - both ride just fine.
But crawling around in the city? Yeah the S is smoother. Though the M3P on coilovers never gets harsh. The bigger the bumps / the worse the pavement, then the *better* it is in comparison to stock M3P suspension. Obviously I dodge the wheel-swallowng potholes of course (in either car).
Both cars generally feel good over railroad crossings by my standards. Of course some railroad crossings are far worse than others. One unmarked abandoned crossing tore up $7k of damage under a loaner Model S. :|