London:
Parliament:
1)BMW [E90?] and Toyota Celica behind the Jaguar;
2)Grey sedan behind Tanner;
MI6 Headquarters' explosion:
3)Two interesting cars on Millbank:blue car on the left and grey van in front of the cab (Chrysler Voyager?);
4)Audi (A4?) and a Mercedes truck (Sprinter?) to the left of Tanner;
5)Toyota Aygo in front of the Sportage;
6)Black sw (BMW?) behind the Jaguar;
The new MI6:
7)Blue car (VW Polo?) in the higher left corner, when the Range goes inside the new MI6;
8)Strange convertible in the tunnel;
M's poetry:
9)Grey Citroen behind the Fiat (C5?);
10)Three vehicles behind Silva: another 2006 VW Polo, BMW, 2003 Toyota Yaris;
11)During Bond's running, there are some (but blurry) cars: Land Rover Freelander 2, 2001 Vauxhall Corsa, Land Rover Discovery 1 (that's all I noticed);
12)Behind Bond, two blurry cars: 2007 Fiat Bravo on the left, 1996 Ford Fiesta on the right, behind the BMW;
Bond steals M:
13)Grey hatchback behind Bond (Toyota Yaris?);
14)Black wagon in the background (Mercedes C-Klasse?).

Shanghai:
I noticed a brown sedan to the left of the Mercedes.
That's all.

Hi! I've seen many scenes of the movie very carefully and I noticed (maybe)some interesting vehicle in the background:
Let's start with Istanbul:
1)When Bond goes out from the palace, there are a blue car on the left and a yellow cab on the right, but they're both blurry;
2)2006 VW Polo in front of the Land-Rover;
3)Grey sedan, when Patrice runs on the bike;
4)Grey sedan (Renault Laguna I?)immediately after;
5)Red van in front of the H100;
6)Renault Megane II behind the Land-Rover;
7)Renault Megane Sedan I (but too blurry for me);
8)While the Land-Rover is running in the wrong direction, there are some interesting (but blurry) vehicles: 2008 Fiat Qubo, Renault (Megane II?), yellow cab, 1998 VW Golf, 2005 Ford Focus II, 2010 Dacia Duster;
9)1998 Ford Focus, when Eve shoots against Patrice;
10)Behind Bond, Ford Transit on the left, Renault Megane on the right;
11)Grey sedan, when Eve chases after the train.