EMU between Mumbai-Pune:
1) Not possible as the distance of 190 Kms between the two necessitates provision of washroom in coaches, which no EMU has currently
2)assuming we over ride the objections to lack of toilets, the second issue that arises is of high gradients. Suburban tracks do have their fair share of high grades (1:25 grade, for instance on harbour line, which is why Mumbai was the first section to be electrified) but they are for short distances and by having high attack velocity one can easily overcome them. Bhor ghat on...
more... other hand is 20+ Kms stretch and require some very serious hauling and braking power. The motors on EMU are roughly in range of 250 Kw [1] and hence even with 4 MC (which means a 12 coach set) the total power is roughly 1 MW. for comparison WAP 5 has 4 MW total output. Distributed power helps but that doesn't solve many issues.
At the end, if we use EMU's, there would be no significant advantage as they aren't really meant for such long distance travel (no padded seating in second class, limited seating available etc), have lesser motive power than mainline trains, would require bankers while climbing and still end up eating a valuable slot on the highly congested line.
EMU could be a good idea if routed via navi mumbai, but no connecting track exists at PNVL side.
[1]
click here