try to define your 1-2-3 reads. for example pick a lightsource and render the car appropriately. you have lots of reflections but lacking the form description
on sketch 1 make the background taller so the its not pinching that looks kinda awkward.
i know it's a loose sketch but it could use better wheels (it looks too small) which gives the car more of a stance. giving it an aggressive, athletic look to the wheels can make the sketch appear far more attractive.
I 2nd Dfish and angeladay's comments..Seems like your proportion works out pretty well, perspective looking pretty good.
The looseness of the lines give them more dynamic quality, but be careful with the extra hairy areas (too many lines going over and over). For extra 3-5 minutes (after the sketch) just emphasize the character lines using french curves, so the sketch would read better.
Try concentrate to make the first read of the sketch pop (the nearest part of the car to your audience's eyes).
Add a little bit more interest on your wheels, they help to complete the overall feel..just kinda like applying the tire shine on your tires after washing the car, it completes the look.
Go a little easier with the surface details on the door panel area...you don't want to have many crease lines converge to one point (sketch 3).
the taper in the rear window looks very extreme? is this a 2 plus 1 type seating? I think putting the Alfa style grill works for the front but the rear seems really narrow
I second the above comments. it looks preety good, i love them. good work
"For God hath not given us the spirit of fear; but of power, and of love, and of a sound mind. " Vexed & Glorious as ever _________________________ ---------GRAFFITITECH---------
Everyone, thank you so much for your opinions and advices.
Ferrari12//I agree. Dfish// it seems like reflections casted on the body of a car makes 1-2-3 values very confusing. To me, all sides of a car look bright. Meanmini//thanks for your tip. I didn't know about this.
Here is a development sketch from those ideations. If you could nail me again, would appreciate a lot.