Dumb question on RPM.

The only possible way for you to alter the rev's of your engine at a given speed is with actual physical changes to the drive line / running gear.

Larger / Smaller tires, Diff centers, Different gears inside your transmission (numbers of teeth) etc.

If you had dragging brakes, or were heavily loaded, towing etc. the engine would simply become less efficient and use more fuel but the rev's at a given speed would not change.

I do not know the specifications for your make of vehicle, but im sure the answers could be found online with a little searching regarding the rev's the vehicle is known to do in top gear at 100km/h... personally id have thought 3000rpm was a little on the high side.

My guess would be, if you are getting a different reading now the cause is electrical. Unless that is you recently fitted new tires etc.

Lower rev's should equal better economy but it really just depends on the load on the engine.

Travis.

If you have an automatic then a dragging brakes could need more revs to maintan your speed. But I do not know whether you have an auto or not as I don't know a lot about your car.

Lika sTravis said. Yes about the revs but other factors come into the formula like load, the environment (strong headwind with a roof rack is a killer), terrain (sand, mud) etc.

Phil

SDG
To have that much change yours has to be an auto unless there has been a previous electrical sensor fault.
To have brakes dragging since 96 I would imagine they would wear out fairly quickly and have to be replaced often, if dragging that much. Not to mention the overheating of the brakes.

Is is possible since 96, you have been driving around with the overdrive/lockup button deselected and now someone has pushed that button and the revs have dropped because it now find the highest gear?

It seems about the right amount of revs difference for that to happen.

Lower revs don't necessarily give better fuel consumption.
You didn't mention the economy you do get.

Ps Did the brake people also change the rear axle /diff for one which has a lower number ratio??? This could account for the revs drop.
Have you looked to see if the diff or axle has been recently replaced?
ie clean marks on bolts and fittings. I have seen this happen before on cars.
If it has, your front and rear diff ratios won't be the same and selecting 4wd will cause windup, suck most of the engine power and cause immediate transmission/driveline damage.

Now there is some thoughts associated with the problem.

As a previous owner of a 2.8td Patrol I can assure you that the RPM you are now reading for 100kph (ie 2600rpm) is exactly the same as mine was. My patrol was fitted with 265 70R16 BFG All Terrain tyres.