Fuel in the UK is £1.30 per liter. At the present exchange rate, that equals around $2.00 per liter. There are 3.8 liters in a U.S. gallon, putting a milk jug volume of fuel in the UK at an astonishing $7.60. This is quite simply why a 2.0-liter turbo diesel inline-four makes sense in a 3-series in Europe.
My daily driver in the USA is a 2009 BMW 328i sedan. The 3.0-liter inline-six puts out 230 hp and 200 lb-ft of torque through a 6-speed manual gearbox. It is a quick car (0-60 mph is 6.1 seconds according to BMW) but needs to be revved to really boogie along. I love the car and enjoy the handling balance as well as the 30 mpg highway economy.
My sister-in-law’s wedding called for a trip to England so I thought the perfect transport for the visit was to try out the 2.0-liter diesel version of the 3-series. As the USA already has the very powerful 335d, I thought the bread and butter 320d with the 6-speed manual gearbox was a more fitting companion. The engine was recently upgraded and puts out 181 hp at 4000 RPM and 280 lb-ft at 1900 RPM. So, while it is around 50 hp down compared to my 328i, it is 80 lb-ft stronger. I borrowed the wagon version of the 320d during this trip due to some family cargo needs so it’s a bit heavier than the sedan version (165 lbs according to BMW).
So far, I’m averaging 37 U.S. mpg (indicated) under aggressive driving in the diesel Bimmer. I’m sure it wouldn’t take too much work to bring that figure into the low to mid 40 mpg range without getting bored to death by the pace and maybe even crack 50 mpg on an easy highway run. Based upon my experience with my 328i sedan back in the States, I think that car would return 21-23 mpg in a similar driving environment compared to 37 mpg in the 320d. That is a huge difference.
What you lose out on with the diesel is the high RPM horsepower and glorious inline-six soundtrack. I also much prefer the throttle response of the 3.0-liter gas motor. It’s not just the ever so slight turbo lag of the 320d, it’s the syrupy characteristic of the oil-burner. It just doesn’t feel sprightly and perfectly connected to the throttle pedal like the gasoline version. You also learn to short shift for the best acceleration. The engine will rev to 5000 RPM but there is little use in using anything much past 4000 RPM, especially in the higher gears. The BMW engine is happier to rev then most diesels but it still is a mid-range motor. BMW makes a twin-turbo version of the 2.0-liter engine that develops 201 hp and 295 lb-ft but it is only offered in the 1-series. With this latest single turbo version making nearly the same power and torque, I don’t see BMW continuing the twin-turbo version or at least not expanding its application. Look what the German company did with the new turbocharged 3.0-liter gasoline engine, they dumped the twin-turbo and went with a single setup.
In the end, I have great respect for the 320d and see it as possibly the best (or at least most logical) setup for a 3-series if you live in a land of expensive fuel. It is still a very fun car to drive and is quite quick (BMW claims the 320d sedan will hit 60 mph from a stop in the low seven second range). But, BMW’s 328i in the USA is still very frugal given its performance and doesn’t need all the expensive add-on exhaust scrubbing technology to meet the strict emission standards in our country. Still, if fuel skyrockets once again and Americans demand greater fuel efficiency, it’s nice to know that BMW has impressive options ready and waiting.