I never understood the point of these kinds of websites.
Never the less, I would create a free newsletter containing "increase your gas mileage" tips. You could probably find enough PLR material on this topic to create a yearlong newsletter. Once you get that newsletter going then you can pimp them things like cpa gas cards, clickbank products related to cars, gas mileage accessories like oil adatives, fuel injector cleaner, basically anything related cars. Maybe even insurance offers.
Try using using adsense for onsite montization. Although I'm not sure how well that would work if you have little to no content on your site?