I see no need for this in the automotive platform. Expensive and techs who can't fix trons for a little lag that only shows up at the track. Turbos run hot and trons hate heat...
They could do the same thing, and have, with compressed air. Specifically around 1994 using compressed air (a LOT of compressed air) to spool up the turbos on V16 CAT gensets so they could drop full rated load on them. Switching full load from the battery room UPS, rather than wait for the turbo with gradual load being applied. There were several V16 gensets to power the intel fab over in NM and when the gensets could not take full load being switched to them the battery room caught fire from switching back and forth. They abandoned the plant for a few days and it was a challenge to put the battery room fire out.
The other solution aside of hot-rodding the generators: They brought another huge powerline in to the plant to help solve the 'truck hits the only powerline' and takes it out problem.
6kw from a 48v system. Yeah... that is interesting. In commercial or industrial application, you wouldn't even waste time with anything other than 480v because of efficiency.
Think about running your air conditioner for your house on 120v. No way- too inefficient. Just wow.
Lithium ion batteries would do it. As was pointed out, it's only a momentary boost. So a lithium ion battery bank at 48 volts could supply a 2-3 second charge to spool it up, but in all reality it would be less than a second of current inflow to start the process, then taper off rapidly. The problem I see would be recharging the battery banks in say stop and go traffic with somebody running it hard. I could see the battery bank depleting, and it going into a reduced power mode, and the owners of those high end cars starting up a class action lawsuit because it can't deliver the power at all times.