Back in the day, six-cylinder Mustangs and Camaros were dismissed as secretary’s cars. You could slap a set of Cragar SS chrome rims on a straight six, but the exhaust note always gave it away. Musclecar fans debated horsepower, not fuel efficiency. Flash forward forty years and things have changed. Folks are pitting Mustang gas mileage against Camaro gas mileage. The cutting-edge naturally-aspirated V6 engines in the current Mustang and Camaro are both powerful and thrifty on gas (when driven conscientiously).
The 2011 3.7-liter V6 Mustang is rated at 30 miles per gallon (MPG) on the highway (when equipped with the six-speed automatic transmission), while delivering a remarkable 305 horsepower. I was lucky to be on hand to witness the Mustang 1000-Lap Challenge at Bristol Motor Speedway back in June. After spending a good part of the day with Mustang Vehicle Engineering Manager Tom Barnes and the engineering crew, I gained a raft of insight into how the original pony car was transformed into fuel-efficient fire-breathing beast.
Want to know how the team scored a remarkable 48.5 MPG in the test? Que up the video …
While purists may argue that only V8-engined cars can be considered true muscle cars, it’s tough to argue with 300+ HP and sub-six second 0-60 times. (“But mine goes to eleven!”)
I first caught drift of the new-found emphasis on musclecar fuel efficiency when I spent some time with General Motors (GM) Performance Engineer Thomas Gardner, back at the 2008 SEMA show. Tom mentioned at the time that they expected at least a 27 MPG rating for the 2010 V6 Camaro, although there were tweaks yet to be made. The GM team subsequently succeeded in wringing another two highway MPG out of the car to score a 29 MPG highway rating. This was the opening salvo.
We continue to chase the story and believe that there are further improvements down the pike. While some folks may be shocked that the automatics can be more fuel-efficient than the manuals, there’s no surprise that both the new Mustang and Camaro use six-speed transmissions. Tweaking the sixth gear ratio is one of the keys to achieving optimal highway mileage, in addition to aerodynamics.
This is where aftermarket products shine. Improvements can be made after the fact and even as part of routine maintenance … say at tire replacement time. The 2011 V6 Mustang automatic is equipped with fuel-efficient 215/65R17 Michelin Energy Saver low-rolling resistance (LRR) tires from the factory. While LRR tires are becoming increasingly common, they’re not available in sizes for all cars. The Camaro is a case-in-point.
Custom sixth gear ratios, optimized for specific cruising speeds might not be out of the question. (This practice is fairly commonplace with VW TDI enthusiasts.) Boatloads of torque open up the possibilities for those who are willing to drop a gear to pass at highway speeds.
There’s evidence to suggest that lowering suspension height may lead to better gas mileage.
Eibach Springs performed tests with their Camaro SS Pro-Plus Performance Handling Package that indicated a 13% increase in MPGs after installation of the kit which includes lowering springs and anti-sway bars. In addition to the reduction in aerodynamic drag, the ability to carry more speed through the corners reduces the need to apply as much throttle on the way out.
So how does the Dodge Challenger fit into the gas mileage battle?
Although the Challenger R/T automatic’s HEMI V8 engine features cylinder deactivation at cruising speed, we haven’t had the chance to test it yet. We did test an early 2009 Challenger V6, equipped with a rather archaic 4-speed automatic. (The 4-speed auto was replaced with a 5-speed unit later that model year and the aging V6 is due to be replaced with the new Pentastar V6 in the 2011 model year.) Despite being hampered by the 4-speed, the original V6 Challenger achieved respectable MPG results.
We expect the 2011 V6 Challenger’s highway mileage to fall slightly under the Camaro’s mileage.
Like the Camaro, the Challenger has a relatively high aerodynamic drag ratio and may also see significant benefit from lowering springs. A range of LRR 215/65R17 tires are available to fit the V6 Challenger from Goodyear, Michelin, and Continental. (If Dodge is willing to lend us a 2011 Challenger V6 for testing, we’d be more than willing to tackle the task of testing.)
– by Daniel Gray