I just took a look at BMW's entire lineup. I'd rather stick with my 300D, but if someone held a gun to my head and forced me to buy a new BMW, I'd probably go with either a 328d or 320i sedan or an S1000RR. The 328 would probably get the best fuel economy of the three, but isn't available with manual transmission. The 1000 would be the most fun, but the least practical.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 401,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 26,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.
99 Mazda Miata 183,xxx miles.