I remap lots of cars without going near a rolling road.
Rolling roads are massively useful in extracting every last bhp from an N/A petrol car, but of pretty limited use for anything else really.
Diesels you tend to be smoke limited so can map upto that point with or without a rolling road, and petrol turbos you tend to be knock or EGT limited, so again its pretty easy to get very close to optimum without a rolling road.
I do use rolling roads on some of the petrol turbo cars I map though for just reasons of practicality, if you are talking about 400-500bhp per tonne it means to do it on the road and have time to map it properly your up in 4th/5th/6th gear to do so for the revs to raise slowly enough, and that means going around at double the national speed limit a lot.
I also feel that you cant properly map on a rolling road only, I quite often have rescue jobs where people have had a car mapped on the rollers but it just doesnt quite drive right at part throttle and low rpm etc, its very hard to feel what a car is doing on the rollers and also its a total waste of money to be spending the hours it takes to get the transient fuelling correct on a rolling road when it can be done better by feel when you drive the car around.
112bhp on a bog standard (ie not upgraded intercooler or injectors) 65dci I really dont think is possible TBH, not on the rollers I use anyway, but would certainly be interested in seeing it if it did happen.