Hi y'all. I know this has been brough up before, but me and dumpshock search function are not friends. (Also, I'm not sure if a final answer was ever settled on, though I think I recall a Dev throwing us a few ).

When mod-ing vehicles, how does the math work?

Are the "-10%" to statistics cumulative (for example)? (So smart tires and sidecar would drop your motorcycle by -40% accel and spd, as opposed to -20 & -20).

What about costs, on modifications that are (for example) spd x accel x body? Do you use the base spd & accel, or do you recalculate after each mod?

Thanks.

Per Arsenal, page 131, all percentages that modify Speed and/or Acceleration are calculated by the base speed of the vehicle. Smart tires and a side car drops a motorcycle's speed by a walloping 40%; might wanna consider a fully customized engine to cut that penalty to 20% of the original speed.

Only four mods, from what I can find in Arsenal, have a nuyen cost based on the speed and/or acceleration. Customized Engine (counting Speed & Acceleration as separate), Improved Economy, and Turbo Charger. For ease of math, just use the base speed stats of the vehicle, not the modified stats.

Arsenal(2nd printing) p131. If yours doesn't have this, might wanna check the errata files.

Percentages: Some modifications raise or lower the acceleration and speed of vehicles by a specified percentage value. This percentage is always based on the vehicle's basic value. For example, a vehicle with a Speed value of 120 that recieves a speed increase of +20% has a new Speed value of 144. If, at a later time, it gets another modification that reduces Speed by 10%, this would result in a new Speed value of 132(144-12).

While the devs suck a bit at showing their work, it fits. 10% of 120 is 12. 20% is double that. The base shifts up twice, then down one. 120+12+12-12=132.

I think this means that with all the mods and accessories that affect speed(too much armor, sidecars, smart tires, maybe some others), its possibly to get a vehicle to have 0 speed.

*face palm*

Right, Arsenal. Not dumpshock, not the Arsenal errata.

Neh, can't win them all.

I think a 80% speed penalty is the worst you can get, and that's only for motorcycles. AFAIK those are the only mods that negatively impact speed, including a model variant of said motorcycle (see Arsenal, page 107) and short of GM's discretion once you're overmodding a motorcycle.

Though it would be interesting to see a go-gang try this; a Dodge Scoot with smart tires, a side car, and an armor rating of at least 5. Won't get more than 20mph with that (speed rating of 24); half that if it's a slower version of a Dodge Scoot. Might actually see a speed of 0 if a troll tried to use it without a metahuman size adjustment, at GM's discretion.

While it's not official, the Structural Reinforcement modification (courtesy of Synner) goes up to R3 (for +3 body), and imposes a -10% speed penalty per rating point.