Car Points Question

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  • March 16, 2015 at 9:00 am #7463
    William Lin
    Participant

    Just curious, who calculates the point system for the car classifier?

    My car, e89 Z428i has more points and is in a higher class than an e89 Z435is. Even though it is has 95 less HP and 100 less TQ. Seems a little funky lol.

    There probably is a good reason, just wanted to ask the question.

    Thanks!

    March 16, 2015 at 9:08 am #7464
    William Lin
    Participant

    My guess as the potential reason is the difference in engine placement and weight.

    The 35is engine is heavier, larger and placed more in front of the front axle. The 28i engine is smaller, lighter and is placed more behind the front axle. Is the rationale that the 28i is dynamically better so it is classed higher?

    Can’t ignore the power differences though. 0-60 in 5.6 in the Z428i vs 4.6 in the Z435is.

    March 17, 2015 at 5:24 pm #7469
    Jack Yu
    Moderator

    Jeff can answer the “who” and “when” it can be fixed.

    I will say that it seems incorrect that the 428 would have more points than the 435.

    March 17, 2015 at 10:28 pm #7470
    William Lin
    Participant

    Thanks Jack. After your comment made me realize I could just check to see how the other N20-engined cars are classed.

    228i = 41 Base Points, B
    328i = 42 Base Points, B
    428i = 40 Base Points, B
    Z428i = 49 Base Points, B (52 points w/ ZSP)

    Z435i = 47 Base Points, B (49 points w/ ZSP)
    Z435is = 47 Base Points, B (49 points w/ ZSP)

    It’d be awesome to just have the same number of points as a Z435i. Including the ZSP, I could be in B! Woohoo!

    March 19, 2015 at 10:51 am #7494
    Matthew Visser
    Participant

    The Z428i is listed as as almost 300lbs lighter than a Z435is (3263lbs vs 3549lbs). The rule of thumb is that each 100lbs is worth roughly about 1pt. So that is 3 points. The Z435is has more torque (we mostly use torque, not HP) and that accounts for why it is only 2 points and not 3 points. Keep in mind that the benefit of HP/TQ (and points assigned for extra HP) drops off as we get into higher HP/TQ. The 28i engine already puts out a pretty healthy 260ft-lbs.

    March 19, 2015 at 2:46 pm #7497
    Jack Yu
    Moderator

    Yeah it’s lighter, but it’s not faster overall, so I still don’t get why it’s two points higher. Starting them both at 47 then adding points doesn’t make sense to me since they start with different HP and TQ. It would make more sense to start the 435 higher and then add points to the 428, making them even at most.

    Is this the only BMW model where this happens? How about the 128 and 135? The e36 325 vs. M3? 328 vs. 335? and so on…Why is this special?

    March 19, 2015 at 3:26 pm #7498
    William Lin
    Participant

    Thanks guys. I’ve heard that the most important 0-60 type metric with regards to power in AX is 30-60.

    Z428i
    0-30: 1.9 seconds
    0-60: 5.8 seconds
    30-60: 3.9 seconds

    http://www.edmunds.com/car-reviews/track-tests/track-tested-2012-bmw-z4-sdrive28i.html

    Z435i (couldn’t find 0-30 specs for Z435is)
    0-30: 1.6 seconds
    0-60: 4.7 seconds
    30-60: 3.1 seconds

    http://www.motortrend.com/roadtests/convertibles/112_1006_audi_tts_bmw_z4_nissan_370z_porsche_boxster_comparison/specs.html

    Wish I could get the same data from the same source.

    In comparison:
    228i
    0-30: 2.0 seconds
    0-60: 5.1 seconds
    30-60: 3.1 seconds

    http://www.edmunds.com/bmw/2-series/2014/road-test-specs1.html

    I guess we could do more comparisons and really figure this out but it does seem strange.

    • This reply was modified 9 years, 8 months ago by William Lin.
    March 19, 2015 at 7:17 pm #7503
    Dennis B
    Participant

    Perhaps there are some points built in for 135i for the electric LSD?

    128i does not have it whereas the 135i does.
    AFAIK both Z428i and Z435i have it.

    Still, I also find the Z4’s base points strange in contrast with the 1series (128i = 41, 135i = 46).

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