I think that the suitability of your locally-available 89 AKI has more to do with the actual AKI of that fuel, than with your altitude. It may be fine, it may produce less power and mileage than locally-available 91 (which is the factory recommendation).

My local 89 was fine, no power reduction or fuel consumption increase compared to 91 AKI. Fuels vary widely across North America, and I don't know what fuels in your locale are like. Your dealer may be right, but I would check mileage with both fuels before assuming that.

:xoutpost:
You're gonna love that thing. I hope your wife likes driving the power wagon! :bustingup

Provided I stay away from Sams Club and reservation stations with her X5 I think it's pretty consistent. My PW runs fine on 85 octane at 5-6K feet, but you usually on find that on the reservations. It's usually 86 or 87 elsewhere.

Altitude definitely does play a factor in dropping down to a lower octane rating. From reading (a few years ago), oftentimes, a 2,000 increase in elevation was enough to drop an octane rating with no appreciable loss in power or premature detonation due to the lower cylinder pressure.

LOL! Yeah, I haven't told her that part yet. If you hear no more from me after tomorrow, it's because she ran me over. <grin>

I agree in principle that altitude does reduce the need for a higher AKI fuel. I just think that fuel variation is greater than altitude impact.

If in fact you have sufficient altitude to reduce pre-ignition significantly, you likely have sufficient power degradation from the altitude to notice that impact as well, IMO. The appreciable loss in power is significant, but is due to the altitude more than the fuel in that case. If you always drive at that altitude, it likely isn't apparent.

3.0 = grocery getter. 4.8 is, well, i think you have already figured that out. wooowhoo! welcome.

> Everything you wanted to know about gasoline, including altitude effect on octane requirements:

http://www.chevron.com/products/ourf...w_complete.pdf



"For newer engines the change is almost zero because the ECM leans the air-fuel
mixture and advances the spark timing as altitude increases."

(Page 8)

Agreed JCL. There is a definite difference between the reservation / Costco gas and something like Texaco.

First - Congrats on making it here. Lots of real BMW evangalits found here and many who can offer help and advice on just about anything and everything that could come up.... so, welcome.

Nice purchase.

In terms of the resale value of the 3.0 v 4.8, clearly the 3.0 will hold its value more IN THIS MARKET. First of all, you have a declining economy, so people want to spend less - which makes getting into an lower cost BMW more attractive, second, as a result of this economy, the gas prices have skyrocketed and getting 12-13mpg in the X5 and putting in $4.50+ gas twice a week (depending on how you drive/commutte) can scare the hell out of people. I just sold an Audi S6 - a v10 - it was selling bags of sand in Miami.

One cool mod, electronic, not performance is the DVD. Check out the other thread in the formum called, "DVD in motion.." i talked about what I did to my DVD player in the car - very cool.

Anyway, congrats and welcome!

I'll check it out thanks.