Well done boom for facing the problem - if you gave up smoking you can give up excessive eating.
1 year ago, I got a new job, desk based. Most weeks, especially in the run up to Christmas, colleagues bought in cake and chocolates and that, combined with my already junk food-heavy diet and decreased physical activity led to me gaining 6lbs between October and January. At that time, I decided I need to do something otherwise I would continue to gain more and more weight.
But, I hate the idea of dieting - don't want to feel bad if I eat anything unhealthy, and also I don't see the point - if I dieted for 6 months, lost a stone, then went back to my previous lifestyle, I would just put all the weight back on and feel like a failure.
The solution, I thought, is to change my lifestyle rather than go on a diet. There were three action points - 1. more exercice, 2. eat less food generally, 3. what i am eating, needs to be more healthy. The aim of the game for me was to get used to these things and make them feel normal - I was changing my lifestyle forever, not untl I lost x number of pounds. I will lead a healthy lifestyle, and my weight will adjust itself accordingly. I will not obsess about how much weight I loose, just focus on making healthy choices (in part, I was inspired by that thread about the mediterranean SIL who ate ham and eggs and stuff for breakfast rather than special K).
Since January I have lost 1 stone 4 pounds, it has been slow, but I guess that must be healthy weight loss (1-2lbs/week?).
For your splurge in the car moments, why not buy some grapes/strawberries/other tasty healthy snack food, prepare them the night before in a tuppaware. Pop it in your bag, then when you are tempted to stop off for food, just get your fruit tuppaware out! Good luck and well done for facing up to it. >encouragement!