The Chrysler 300 fullsize sedan and Jeep Grand Cherokee midsize SUV return to the SRT fold after an absence of one model-year.

The ’12-model vehicles bow this week at the New York auto show.

The move leverages Chrysler’s 6.4L Hemi V-8 that bowed in the ’11 Dodge Challenger SRT8.

The new engine generates 465 hp at 6,000 rpm and 465 lb.-ft. (630 Nm) of peak torque in both the ’12 300 SRT8 and Grand Cherokee SRT8.

The performance numbers narrowly beat the Challenger SRT8’s ratings of 470 hp and 470 lb.-ft. (637 Nm).

Both new SRT8s are positioned as halo products for their brands.

“In addition to Jeep 4-wheel-drive traction and utility, the Grand Cherokee SRT8 takes capability to a new level by giving driving enthusiasts extreme performance for the street and track,” says Jeep President and CEO Mike Manley.

The 300 SRT8 is “for those customers who live for the sport of being first,” says Chrysler President and CEO Olivier Francois.

The 6.4L Hemi benefits from improvements such as high-flow cylinder heads, sodium-filled exhaust valves, hollow-stem intake valves and a higher compression ratio, 10.9:1, than the 6.1L Hemi it replaces. The 6.1L V-8’s compression ratio was 10.3:1 in the ’10 300 SRT8 and Grand Cherokee SRT8.

The 6.1L Hemi generated peak torque of 420 lb.-ft. (569 Nm) of torque in both ’10 models and 425 hp in the 300 SRT8, 5 hp more than its Jeep SRT stablemate.

Expect both ’12 SRT models to take less than 5 seconds to reach 60 mph (97 km/h) from a dead stop, Chrysler claims, adding SRT customers receive one day of professional driving instruction from the Richard Petty Racing School.

SRT stands for “Street and Racing Technologies.”

Due for launch in mid-summer, the 300 SRT8 and Grand Cherokee SRT8 also will feature paddle shifters.

Both brands broaden their lineups further at the New York show. Jeep unveils the desert-themed Mojave version of the Wrangler, while Chrysler formally introduces its up-market S-Line 200.

emayne@wardsauto.com