I've been preparing to run a short-term 4e game, to be shelved until another player in my group is ready to run Mutants and Masterminds. I went over the basics of vehicle rules, since one player wants to run the Smuggler pre-gen in the book, and I'm confused by how vehicles are supposed to accelerate. There are two values listed under accelerate, and all I can find is a brief snippet in the Vehicle Combat subsection of Combat, and it says the two values are for walking speed and running speed?

Wha?

Could someone clean up this pile of drek, and make this just a little clearer? Thanks in advance.

Welcome to SR (any edition) vehicle rules.

Here is what I understand, I could be wrong so feel free to correct me anyone.

All of the speeds are in meters per combat turn. (Don't forget to divide speeds across Initiative Passes). This rate equals a little more than a km/hr, so for simplicity you could probably use the same numbers...

The Acceleration rating for a vehicle is for use in Tactical Combat (Combat that involves more than just vehicles). In this case, vehicles move at rates sort of similar to metahumans/critters. They can move casually (walking rate), or at a faster rate (Running rate). This is all while they are presumably needing to maneuver in a combat sort of situation.

The Speed rating is how fast the vehicle can (reasonably) go in more open conditions. You use this rating to determine relative advantage in Chase Combat situations (Combats inolving vehicles only).

More than likely in a tactical combat situation, vehicles will not need to (or be able to) go perfectly straight for longer than a combat turn or two. But if this comes up, it wouldn't be unreasonable to allow a vehicle to start to actually accelerate up to its full speed. If a vehicle is needing to make sharp turns, avoid obstacles, etc., however, then the acceleration rate is probably more appropriate. Also, a driver can make a Vehicle test to increase their distance. Each hit on the Vehicle Test increases the acceleration rate by 5 meters per combat turn.

This is, unfortunately, not entirely correct
Yes, the walking and running speed stats that make up the Acceleration attribute are used in tactical combat. It is the amount of meters per combat turn you can accelerate or decelerate without making a test, up to the Speed attribute (which is simply the top speed). Multiply the (current) speed attribute by 1.2 and you'll get the speed in kph.
Obviously, you don't use the running speed value in normal traffic. It represents flooring the gas pedal.
With vehicle tests, you can accelerate or decelerate faster than the Acceleration attribute represents, to be exact by 5m per hit on the test (similar to sprinting). Exceeding the Speed attribute may call for another vehicle test with modifiers, up to the GM.

But yeah. The rules are rather abstract.

I hate to argue, but the book never says anything about that.


Movement rate is the rate per turn that a character moves, they have a Walking speed, and a Running speed. There is nothing that indicates that vehicles follow different rules than characters in this regard...

Your way makes sense, and it might have worked that way in a previous edition, but sadly from the way it is written it isn't simple "abstraction" to get to that ruling.

@ kiirnodel, PM'ed a link to A N Other site that explains it well enough for me to understand,

not sure how you guys here feel about cross site posts .. to the "Other site!"

The SR3 Vehicle Rules were a bit more accurate and "realistic" . . but they were so fragging complex close to nobody actually used them . .
Cue SR4.

Right. Where they changed it to: this is the speed you go if you are going at the vehicles' walking rate, and this is the speed if you go at running rate. The vehicle can go faster than that and whatnot, but during the complex maneuvering and heavy stop/go of combat, just treat it like that.

Hm. After actually re-reading all that, I've come to the conclusion that I may have indeed mixed that up with previous editions.

Here's what I thought would be the case:
If the speed attribute wouldn't be used at all during vehicle combat, there wouldn't be a need for it. They could just say "Bike X has a top speed of Y km per hour" instead.
However, it is apparently used in chase combat, as a flat modifier (if higher than opponent, +1 per 10 points, rounded down).

I think, I'll houserule that now to actually use both attributes in both types of combat
Start vehicle. Accelerate with free action for walking or running, complex action (vehicle test) for flooring it. Up to Speed attribute.
Next round: Decide on either decelerating (using the same rates safely), accelerating or keeping the speed.
You still need a complex action per combat turn to control the vehicle.
Going over the top speed incurs vehicle tests with rising difficulty to avoid damaging the vehicle.

Thoughts on that?

sounds interesting. But personally, I would still default to the base rules when the combat/terrain get's really close. If a character is able to keep going perfectly straight for several turns in a row, feel free to let them continue accelerating (at the run rate most likely) up to the speed attribute. But more than likely at that point the combat is moving to a Chase Scene, not a tactical combat. And chase scenes abstract the movement rates to a dice pool modifier based on how much higher the top speed is of the faster vehicle.

EDIT: I wouldn't let someone go straight to the top speed in one round, that would be like going 0 to 60 in 2 seconds... That's also what the Vehicle Test, each hit increases speed by 5 meters per turn is for.

In regards to your edit: Of course not.
Let's say, someone drives a Westwind, with a top speed of 240 (= ~288 km/h) and an acceleration of 20/60, he could only accelerate from 0 to 60 in his first combat turn. 4 turns (~12sec) from 0 to almost 290 km/h sounds good to me for a souped up sports car
A really good driver with ground vehicles skill at 6 (and at least 2 IP, he still needs a complex action to control the vehicle), I'd allow him to use 6 hits on a vehicle test, for a max of 90m acceleration, resulting in a starting speed of 60-90 m/ct in his second turn.

Without that, my changeling courier could almost outrun a stock Westwind in tactical combat (20/50 movement rate, and that's not even maxed out).

Um, Mach_Ten, any chance you could PM that link to me too? That is the sort of thing I was asking for in the OP.

Well, 0 to 60 in 2 seconds, no.
0 to 60 in 4 seconds? of course.
which is just a third longer than one round.
round down to one round and there you go.

how in the hell did I get mixed up ? I thought Kiirnodel was OP .. really sorry .. link to be sent asap.

but the essence of it is in Kiirnodels last post

use the walking / running speeds as metres per combat turn 0 / walk / run / faster / crash

during the complex maneuvering and heavy stop/go of combat, just treat it like that.