1800 RPM @ 45 MPH - Good or bad?

I have an '03 fully-loaded (including automatic) ZTS that I absolutely love. However, I notice that when I drive 45 MPH around town, the car is in 4th gear and registers
1800 RPM. At this RPM, it seems to slightly bog-down, but not too badly. Just for kicks, when I turn off overdrive, it stays in 3rd gear at 45 MPH and registers 2800 RPM.
So my question is, what is better (less wear, but proper mechanical dynamics) for the engine, a constant 1800 or 2800 RPM. It seems to run better at 2800 RPM. While we're at it, which would provide better gas mileage?
Thanks, David.
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On 30 Jun 2003 20:56:56 -0700, snipped-for-privacy@earthlink.net (ragtopgeek) wrote:

What's the speed limit in your town? Here in the UK it's 30 m.p.h. in a built-up area, often less.
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There is nothing wrong with running a modern engine at 1800rpm or even less, particularly on partial load. You will get better gas mileage than at 2800 rpm in 3rd, if for no other reason than all that extra engine churning requires fuel. Wear will also be less, although with today's vehicles a properly-maintained engine normally lasts the life of the car.
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wrote

Personnally with a manual car I would rather run in 4th gear as opposed to 5th if that equates to under 2000rpm unless it was downhill. Modern multivalve engines are alot happier with more revs on the clock than less, mainly due to their less ability to produce sufficient torque at low speeds.
Tim..
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speeds.
I have a Turbo Diesel... happily cruises around town in 5th at 35Mph or more.
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to
less,
i neglected to say that my post refered to petrol powered cars. However if you drive something like a Vx DTi or BMW 320d (multivalve diesel) you'll find they are also not keen to run at sub 2000rpm speeds. Especially the bmw which relishes undieselish 3500rpm+ work.
Tim..
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bmw
:o) Given that I'm posting in a Focus specific group, it would seem nobvious that I'm not driving a BMW :o)
However, yup, fair point re. the speeds..
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