This car is an absolute blast to drive. It's the first car I've owned, and it is well worth the price. A used 318is goes for about $14,000 (Canadian dollars), for which you could buy any number of new compact cars.
Handling is impeccable. This vehicle goes where you put it; the steering is extremely predictable, not too touchy, not too heavy. The integrated traction control (sort of like reverse ABS) keeps your wheels from spinning while cornering and accelerating. There is a lot of stopping power in this car.
The interior is fairly minimal, but roomy for such a small car. I have the lower-end leather seats with no electronic adjustment, but they are very comfortable, are heated, and can be endlessly adjusted. Seats four comfortably if the driver and passenger are about 6' tall. The panel is very clear and well organized. This is NOT a luxury vehicle; it's a very comfortable driving machine.
The four-cylinder engine is very zippy. If you are a raw-power kind of person, get a 325 or better; the 318 is a city driver, or curvy highway master. It performs fine on the freeway though; it just takes a little more time to get up to speed, and the power kicks in at about 2800RPM, so it makes some noise while doing it. Shifting is like butter in this car; a short-shift upgrade would be a very good idea. Acceleration is smooth and feels snappy, but has nowhere near the 'kick' of the 328's six. Still, while driving the 318is, you know you have a BMW in your hands. It's _so_ much fun. And if you shift well, you can take most of those kids in their little Civics with Folgers can exhausts and painted drum brakes.
It's also very, very pretty.
That whole "BMWs are expensive to maintain" myth is just that: mythical. If you take the car in for regular service, it will NOT give you trouble. I had a complete service done on the car after I bought it, and it would have cost about $250CDN including parts and labor if I hadn't put on new tires as well. I am told I can expect to put in about $60CDN per checkup from now on. The only reason the initial service was pricey was the fact that the last owner hadn't serviced it regularly, and a number of new parts were needed. No big deal.
Oh, and mileage is excellent. I fill up every 3 weeks or so, and I drive a lot.
Go buy one. Don't bother with those little Mazda's or Subaru's. You'll be looking for an excuse to drive it.