Keeping weight down is all-important. Which is why I remain in love with the Lotus Elise. It proves that less weight fixes everything - better handling, acceleration, braking, fuel economy...of course in a hybrid, the battery pack is always the vexed question. Even the best batteries are still expensive and relatively heavy.
But even the Elise isn't immune, it's all relative of course, but it's gained roughly 170kg since the Series 1.
But along with aerodynamics... it's perhaps the
most important factor in, as you say... handling, acceleration, braking, fuel economy... pretty much
everything.
When you think how innovative a car like the Audi A2 was, I do find the lack of
real progress over the last 12 years particularly sad. 10 years ago, the A2 was a sub 1000kg
(sub 900kg in certain trim) proper 4 seater, its 3 cylinder TDI engine could easily achieve 70+mpg imp without even trying
(according to Wiki 107.8 mpg & 140 mpg imp were also achieved).
The 1.2 TDI version emitted 81g/km CO2, featured Stop/Start, an Eco mode that disengaged the clutch when the accelerator was released to maximise free wheeling and was rated at 94mpg.
And this was 10 years ago...
In many ways, it's shameful today that we think that 60 or even 70mpg is somehow remarkable for a family car.
the Cruze diesel, which may be able to equal or exceed the new Jetta TDI's level of equipment, refinement and pricepoint.
But not the brand image...
that could perhaps be the biggest stumbling block of all, it certainly is in Europe anyway.
Personally... I don't think GM have a clue, and that's one of the reasons why they got themselves into one almighty hell of a mess, and only time will tell if they can get themselves out of it. I'm still of the opinion that GM's decision to attempt to introduce Chevrolet into the European market will ultimately prove futile.
Here in the US, the sedan (saloon) is king, even on smaller cars like the Focus and Corolla. That is slowly beginning to change, but Americans still like three-box cars over hatchbacks. Personally I prefer hatchbacks and wagons, though larger cars still look good as sedans.
Have to say my preference is for saloons... occasionally an estate
(particularly A4 & A6 allroads, also 159 Sportwagons, that sort of thing), hatches
(the bigger ones anyway) & estates can/tend to be a little
boomy in my experience. Saloons also often have better body rigidity too.