Really? Must definitely be with newer vehicles. For those vehicles I owned with manual transmissions, I always got better fuel economy that was at the upper end or slightly exceeding their average mpg range for the transmission they had. With automatics I was always near middle or slightly lower then the mpg range.
It remains to be seen how the 6 speed on my new Silverado rates...
Certainly I'm speaking about the newer vehicles. And obviously, fuel economy has
everything to do with where you drive and the type of driving you do. If you spend all your time on the highway you'll certainly get better gas mileage than someone like me who spends 80% of their time driving on dirt turnrows and across fields. Vehicles that suck with gas mileage for suburbanites may shine for commuters, etc.
In your new Silverado, something fun to do is to switch your dash display to the setting that shows your instantaneous gas mileage and (since you said 6 speed trans, I'll assume you have a V8 with variable valve timing) watch your motor go from firing on 4 cylinders to 8 under certain driving conditions. Pretty cool....
@Moratinur
I'm pretty sure the person that mentioned auto's over manual on the race track was speaking about drag racing. You can downshift automatics for downhill. And almost every automatic (in the US anyway) has overdrive today. The old school advantages of manual vs automatic are quickly evaporating as automatics become more hybrid.
I was in the dealership today drooling over the new Camaro's. The SS I was slobbering over had the new 6 speed automatic with the clutchless manual shift option. Haven't driven one, but like I told the dealer, if I'd had that thing when I was 17, I wouldn't be here today. I'd be six feet under.
I bought my first car in 1972. It was a used 1969 Z/28. Paid $1200 for it. Sold it in 1982 for $7,000. Today it would be worth > $40,000....
<sigh> And I thought I was robbing the guy. I'll bet he's laughing his *** off at me now....