Because the six has perfect primary and secondary balance, and the four only has primary balance. It shakes.

Also, the six represents heritage and tradition.

With the Mustang discussion, it was about keeping the tradition. But then I owned a Morgan with sliding pillar front suspension and pressurized oil lines from the engine galleries to lubricate that suspension, so the live axle was pretty far advanced by comparison.

I agree with that, especially the vehicle weight.

I would expect the same red line.

Thinking about the specific output, a 2 litre engine making 245 hp equates to 368 hp for a 3 litre. Not bad for the first generation.

Not bad at all. Just thinking about the possibilities for future 1 and 3 series cars is quite exciting actually. A lighter 1-series with this engine and a slightly better looking body would be fantastic, imo.

I know what you mean about the smooth 6's though.

That means it would rev 2000rpm beyond peak power whereas at 7000rpm the 'detuned' six is only 900rpm above peak power. I can't see it myself.

Cool, apparently it only needs regular (91 RON) fuel. So its less thirsty and no longer needs midgrade.

I think that is the same as the current turbo engines. The 35i has a minimum of 87 AKI noted in the manual. You won't necessarily get full power out of that fuel, and they are likely to word it differently in the BMW USA owner's manuals given the variability in fuels in North America.

I'm sure it will run on 91RON but no doubt it will deliver optimum performance and economy on 95RON or 98RON.

BMW used to be more specific on these requirements. In the 2007 3er manual, it states that 98 be used for the advertised economy and power, with lower grades to 91 possible (the N54 engine requires 95 minimum).

In the new X3 and 5er manuals, it simply states quality of the fuel is more important, and that 91 is the minimum octane level.

Wonder if and why they're leaving things out of the owner's manual. :dunno:

I guess the newer engines have 'smarter' ECUs that are more adept at managing the different fuel grades.