Drivetrain
HEMI. 392. Almost, but not quite. Chrysler (like everyone else) designs their engines with metric measurements and the chief engineer at Dodge claims the displacement translation to English units was done after the fact. That’s why this 392 is really a 391, but that’s close enough for the marketing department. If we’re splitting hairs, the heads are only partially hemispherical. Does any of that matter? Nope.
Any complaints about the rubbery interior evaporate you look at the engine’s numbers. Chrysler didn’t just bore out the 6.1 to get more displacement. Instead, the 6.4L shares its tech with Chrysler’s revised 5.7L V8. Unlike the competition, you won’t find any overhead cams, no special direct injection sauce and only 2 valves per cylinder. Despite that, the 6.4L engine is far from retro. This pushrod V8 gets variable valve timing thanks to a trick camshaft, a variable length intake manifold and cylinder deactivation (with the automatic transmission only). The changes vs the old 6.1L SRT engine are transformative. Power is up 45HP to 470 while torque takes a 90ft-lb leap to a horsepower matching 470. More important is the significant improvement in torque from 2,000-4,000RPM. The old 6.1L engine had some odd power peaks and felt out of breath at the top end. The 6.4 on the other hand feels eager at almost any RPM.
Dodge made the Tremec TR6060 6-speed manual transmission (borrowed from the old Viper) standard, a surprising twist in a portfolio that’s automatic heavy. The manual’s shifts are short, the engagement is near perfection and the clutch pedal is linear with predictable engagement and low effort. Should you be a left-leg amputee, a Mercedes 5-speed automatic is available. Don’t do it. While the automatic transmission enables Chrysler’s Multi Displacement System to function, the 6-speed manual is better in every way including fuel economy. Speaking of economy, the Challenger wears a $1,000 gas guzzler tax because of its 14/23/17 MPG numbers (City/Highway/Combined). However, thanks to an extremely tall 6th gear we averaged 19.5MPG over our week with the Challenger and averaged an impressive 25MPG on a long road trip. Real world economy numbers with the automatic appeared to be 1-2MPG lower based on a short drive with a dealer provided vehicle.