What are typical delta-v for deep space maneuvers, used by deep space missions to outer planets or for "interstellar missions" ? For example, Voyager 1 now has 17 km/s speed relative to the Sun. What part of the speed was created by the rocket, what was delta-v of its hydrazine thruster, and what was delta-v from gravitational slingshots (gravity assists)?
Voyager 1: separated from Centaur stage with velocity 18.3 km/s (relative to Earth, Dave Doody, Deep Space Craft: An Overview of Interplanetary Flight, 2010, page 120). Then 76.5N Injection Propulsion Unit of V1 did burn its solid fuel in 43 seconds giving additional 1,7 km/s (?), injecting the spacecraft into Hohmann transfer orbit. IPU was separated, and Mission Module itself has only sixteen thrusters (0.9N each) used only to fine-tuning (statistical maneuvers?). So Voyager 1 (and its brother Voyager 2) had no Deep Space Maneuvers, flying on free-fall cruise with minor corrections, and doing unpowered flybys (gravity assists)..
Voyager 2 should be similar to Voyager 1, and there is plot of its velocity relative to Sun with 4 passive gravity assists: Jupiter in 1979, Saturn in 1981, Uranus in 1986 and Neptune in 1989.
Messenger did Deep Space Maneuver (DSM) at 2005-12-12 with delta-v of 316 m/s (in 524 second burn by using 18% of propellants - same book, page 71), preparing for Venus gravity assist 10 months later. Total DSM count is 5, and there was 830 m/s injection maneuver.
Cassini did one huge DSM of -450.2 m/s with 440 N engine to prepare Venus gravity-assist. (There were several small TCM - Trajectory correction maneuvers). Also it used 626 m/s delta-v to insert itself into Saturn orbit. (page 72 same book or 1998 plans, page 3)
Galileo interplanetary mission (VEEGA=Venus-Earth-Earth gravity assists), was started by IUS solid stage engines, with 3.1 km/s of heliocentric velocity (page 27 of 1992SSRv...60...23D). TCM were: 15.7 m/s TCM-1, 0.7 m/s TCM-2, zero TCM-3 (cancelled), 24.2 m/s TCM-4A, 11 m/s TCM-4B, ~1-m/s TCM-5, 3-5 m/s for TCM-9 and 10, 21 m/s TCM-14. Venus gravity assists added 2.3 km/s (heliocentric). First Earth flyby raised velocity of spacecraft by 5.2 km/s, from 30.1 km/s to 35.3 km/s (heliocentric) and orbit period to 2 years. Second Earth flyby added 3.7 km/s, raising total to 39 km/s (5,6 years period). Jupiter insertion maneuver (JOI) was planned to be -630 m/s. Galileo's "satellite tour" was planned to use total delta-v of 6000-8000 m/s from many gravity assists, which is described as 4-5 times larger than total delta-v of spacecraft thrusters (page 24).
Saturn Atmospheric probe was planned to have 450 m/s delta-v DSM to set up Earth flyby.
New Horizons was planned to have 397 m/s delta-v budget
NEAR used 268 m/s DSM-1 and 932 m/s DSM-2
So, 300-500 m/s delta-v are typical for deep space maneuvers in classic interplanetary missions. Much greater delta-v, of 2-5 km/s was gained by unpowered gravity assists.