How the hell do you think that that all of that is going to result in cost savings over continuing to operate the 185s on TPE, 175s on Welsh services or HSTs on West of England services? I would wager that you wouldn't see any savings recognised from such a course of action for 20 years at least, and in the here and now, it would represent a huge loss.
The 185s do not have "questionable utility" at all. They may not be as fuel efficient or track friendly as Turbostars, but that does not automatically make them the spawn of the devil and totally unsuitable for the regional services they are designed to perform. I feel that the economics of the situation have been somewhat lost in the sprawl of your anti-185 hyperbole.
I try to stay out of the convoluted financial arrangements that exist on the railways. It probably all filters down to the general public and "the taxpayer" eventually though: For starters, in the increased subsidies that the Government would have to pay out to the TOCs when the ROSCOs hike their leasing charges as they feel that they can no longer gaurantee to recoup the costs of new rolling stock over a longer period of time.
Right, thanks to some trawling through various Siemens presentations I have been able to derive an estimate on the fuel consumption of Class 185s per vehicle kilometre, with a figure in the region of 0.59L per vehicle kilometre.
This compares to the figure for the Class 170 Turbostar of 0.454L per vehicle kilometre. Although a Class 172 has a higher power engine it is also significantly lighter so I will assume the figure is reasonable.
IT appears that each Class 185 travels approximately 282800 kilometres per year, which means that each three vehicle train burns approximately 123000 litres of additional fuel per year compared to the Turbostar.
This translates at present fuel prices of roughly 73p/litre of red diesel to roughly
£89790 of additional fuel expenditure.
Additionally the train has roughly 16.5p/train kilometre higher access costs than the Turbostar, translating to roughly
£46660 per year in reduced track access charges. (I am using old figures here from CP4 so this figure is probably an underestimate, ditto using the highest figure for the Turbostar faily of trains I have available).
This translates to
£136,450 in annual savings from fuel and track access costs each year.
As both of these metrics are inflation dependant the most appropriate financing instrument is an index linked gilt. Indeed if ROSCOs can expect the trains to be used continuously until they choose to dispose of them and have a sufficiently strong position to hike rental charges on trains if this is shown to be no longer the case, why should we rent rolling stock from them since we are effectively carrying all the risks of not using them for the full rated lifetime of ~30 years?
So an IL30 gilt has a coupon -0.19% at the present time, so the repayment of the loan for a
£4,500,000 trainset over 30 years would require payments of
£141,500 per annum.
This means that at present fuel prices and the 2009-10 track access charges, buying new trainsets would be £5000 per trainset-year more expensive than retaining the current trains.
This assumes that maintenance of the trains is identically costly in both the cae of the Turbostars and the Desiros.
However this is unlikely to be the case as it is highly likely that the Turbostars have drastically reduced consumption of brake pads thanks to being rather lighter and the fact that both trains seem to rely exclusively on friction braking. (As the hydraulic retarding brake system for the Cl185s likes to cause engine fires when used). The trains are also ten years (or will be closer to 20 when TPE North is finished which is when I propose to dispose of them) and thus are likely to have lower maintenance charges.
I will continue to search for maintenance cost figures per train kilometre, but it appears that they are a large quantity (NR Electrification RUS mentioned 70p/kilometre but I can't remember if that was per vehicle or not) so small gains by the Turbostar over the Desiros will pay large dividends. Currently the Turbostar comes out 1.94p/train kilometres more expensive to run excluding maintenance differentials.