To get it to drop the revs quickly at starting you start it, put it in reverse with your foot on the brake while it is revving and then “blip” the throttle once and the revs will go down to idle immediately. Then you can release the brake and move off smoothly.

This works every time on my P300 for reverse,

 

Throwing the gearbox into reverse so soon after turning the truck on isn't good for the vehicle. During those first few seconds, oil is getting circulated around the various components. Putting it into gear and driving it prior to the idle coming down will likely lead to premature component wear.

This isn't unique to the Defender either.

 

Precisely. There must be an intended reason for the high idle at startup, some have suggested it’s for the catalytic converters, or to boost the battery after a period of sitting. Land Rover programmed it to perform some function outside of our scope of understanding, so to circumvent that is only inviting who knows what down the road. I’ll give it the 20-30 seconds it takes. Now, if I'm rushing someone to the ER with chest pains, then I’ll throw it in gear, warnings be damned.

 

thats the best explanation, and all cars have it, with different levels of RPMs. This is mainly for oil circulation, and it high revs so that the oil will splash everywhere and lubricate before you switch gear and start moving. Not a technician, but this was explained to me several times.

 

I agree with the comments concerning catalytic converters. There has been much hand wringing within the industry on how to heat the cats up more quickly because, well, they don't work efficiently, if at all, when cold. The easy solution is to move the cats as close the exhaust manifolds as possible but there is a practical limit achievable. Higher initial revs generate more heat which is pushed quicker to the cats thus "lighting" them up to do their EPA mandated duty. I could argue that the time spent at high revs pushes more untreated gasses into the atmosphere than at low revs but don't have the data to pass judgement.

However, I would argue that starting an engine and maintaining high revs before the oil has a chance to circulate is more harmful mechanically than at low revs...I rather do not like the fact that mechanical integrity is sacrificed for a few moments of CO and NOx emissions.

 

Well, I would guess that the people designing our vehicles, having advanced degrees in automotive engineering, and the fact that JLR would not purposely program the vehicle to rev high upon start if it was going to damage an engine that they warranty, and would cost them huge amounts of money to cover such damage, know a tiny bit more than the average armchair mechanic. So I do not really believe they are sacrificing mechanical integrity. I’ll stick with trusting those who know more than I do.

 

Likewise, having spent a fair amount of time professionally wrenching on BMW's back in the day, I have a good understanding of engine mechanicals. Coupled with a degree in Metallurgical engineering, I know that engineering a system design is fraught with compromises. As stated earlier, the engineering problem is how to heat the converters so that they begin to operate as designed as soon as possible. This is with the understanding that EPA has dictated the standards to be met. The solution, that likely all manufacturers adopted, is to run a cold engine, cold engine fluids and exhaust system at elevated RPM for the sole purpose of quickly heating the converter to meet EPA expectations.

Undoubtedly, there are some engineering tweaks, such as low viscosity oils for example, to help minimize damage but key word here is dictated...which means manufacturers have to meet certain emissions criteria to sell cars here in the US and elsewhere. Would JLR or any other manufacturer sacrifice some additional wear, minimal as it probably is, for the ability to sell cars here in the US, absolutely they would. It is a compromise for a problem which boils down to emissions vs. wear.

 

Its my opinion that JLR caring about the engine longevity past the warranty period is admitting facts not in evidence. (Note that this goes for all auto manufacturers, not picking on JLR here)

The engineers might care about making an engine live as long as possible - and they might even design something that does so - but the real decision makers that dictate what gets made and how -- are the bean counters and the suits who are looking at predictive data analytics to determine exactly how durable those engines need to be in order to maximize shareholder value.

Having known a couple of the old school GM engine designers who worked on the old IDI diesels, there were definitely considerations other than power, efficiency and durability when it came to their designs - and they'd be the first ones to tell you so, after a few beers.