The Bond Bug, but only 'cos I like a laugh. It would also give my wife someone to look down on, and cut up and out-corner, when out in her Smart.
The Rover 3.5 litre P4 saloon (the Queen drove one) - oh no, hang on, Chrysler already did that with the 300 CRD which does look remarkably similar from some angles.
I do also find myself looking at a new model and wonder what on earth they were thinking of ditching the old one. One example that always sticks in my mind was the Mazda 323, of N and P reg vintage. It looked to me quite a sleek little 4-5 seater with very smooth off-beat styling (and 'slitty' headlights!) and IIRC it even had the option of a 2.5 V6. I even had it pencilled-in as my first non-company car after leaving BT. So what did they replace it with before I could get one? Something so nondescript, I can't even find the words for it. They've moved on again since with the Mazda 3, but they've still still not wandered far from the mainstream.