Z4M diff & buying sat nav/tv kit separately

[Screamer]

Hi all,

I'm thinking of buying either a 3.0si or M Z4 soon, once my RX-8 PZ has sold (http://www.pistonheads.co.uk/sales/382962.htm). The 3.0si appeals simply because of its avoidance of band G tax, but i'm very much aware & tempted by the M's better looks and, more importantly, handling upgrades - namely the swapped steering and the LSD. My question is this: what difference does the LSD make? My understanding was always that you'd have trouble making a non-LSD'd car oversteer/slide because the the 2 back wheels are never forced to turn at the same speed, yet I see many photos and videos disproving this. I'm concerned because, from what I hear, the Z4 will tend to understeer, but certainly in the M models, you can correct this by inducing oversteer by adding more power. Will a non-LSD'd car simply understeer more and more in that scenario? Seeing as my RX-8 has a LSD, it seems like something I don't want to do without, yet I find it hard to believe that all non-M models of the Z4 are dynamically flawed. Do non-M models get some electronic trickery to emulate an LSD or something similar?

And here's my second question: Can the navigation/bluetooth/connecteddrive/tv system be purchased as a kit after having bought a car without it and then either fitted by a dealer or DIY'd? I came across a forum in America (I think) in which a member seemed to have done just that, but i'm struggling to find info on how much the kit would cost without fitting, and what sort of instructions are available... Is a workshop manual available for the Z4 and/or would the kit come with instructions normally intended for the dealer?

Thanks for any info!

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Anyone?

[Nano2nd]

there are alot of questions!

i test drove both back to back, do that then decide

re the second queston, i would say the nav is extremely difficult to retro fit as its heavily itegrated into the dash... its also not great, well not compared to my old tom tom IMO of course... bluetooth is shockingly bad at anything over 50 mph

[Screamer]

Thanks Nano. I'm having a bit of trouble getting to drive both, actually. I got to drive an M roadster in Liverpool and a poverty-spec 2.0 non-sport roadster too. The M was fantastic, while the 2.0 wasn't anywhere near my RX-8. I'm hoping that the sport model's sport button that increases steering weight combined with the firmer suspension might make the car less floaty (much like the new TT)... Like you say, I'm just going to have to find somewhere that has both a sport (i'm presuming that it doesn't need to be a 3.0si - all sports models should handle and feel the same? Should a sport coupe feel any different to a sport roadster?) and an M.

In what way is the sat nav rubbish? From the photos etc that i've seen, it seems to be a fairly high-res system with nice enough graphics (unlike the RX-8's optional one)... Presumably bluetooth quaity limitations apply in pretty much any car - surely it's more to do with the fact that the phone is moving at 50+mph than the Z4 specifically..?

Thanks for the reply!

[Nano2nd]

i didn't try an si but i was under the impression the sport had "sport" suspension. i didn't notice much difference in ride(they are both choppy) but grip on the M was alot better (less traction light action) also the brakes are light night and day, the sport was also a LOT quieter...

the nav looks nice sure, but its additonal functions rerouting, POI etc are limited. it also doesn't do full postcodes and in some cases does do street numbers only junctions (my street for example) though there is a new version of the DVD out for 2008, but i haven't tryed it.. nore am i paying the £100 upgrade fee to try it!

i think the B/T comes down to road noise on the M, those are some big fat low profile tires

[Gids]

The nav install has been done be someone on the old z4um.com but it involves hacking the dash apart and being reasonably savvy in the electrics department. Find one with it already in... much easier