The problem with replacing a successful car is that you have to make enough improvements to make it different, but not enough to alienate the folks who loved the old one.

Acura pulled it off with the new 2014 MDX.

Outside the changes are more evolutionary than revolutionary. In fact, you’ll have to look closely to notice the subtle differences. Underneath, however, it’s a whole new car.

The old MDX shared the same chassis as the Honda Pilot. No more, for 2014 it gets a new chassis. It has a 2.8 inch longer wheelbase. Acura calls it the result of Advanced Compatibility Engineering (ACE) and claims it’s stronger and safer.  While the body doesn’t look radically changed, it is lower and narrower. You can watch Acura’s video about the changes  here.

The engine is new as well. This year it has a 3.5 liter V6 replacing last year’s 3.7 liter. Although its 290 horses is 10 fewer than last year, you’re not likely to notice. One advantage is that the new engine (together with the sleeker shape) gets better mileage. The all-wheel drive version delivers 18 mpg in the city and 27 on the highway. That is much better than last year’s 16 city/21 highway. For the first time you can now get a 2WD version. Living in Phoenix I don’t need the AWD version much, and I can get an extra 2 mpg as a result. The engine is mated to a 6-speed Sequential SportShift transmission. You can go automatic or try the paddle shifters (although I’m convinced few people ever do). You can also switch between comfort and sport modes, but I couldn’t tell much difference in my daily commute.

Inside Acura has upgraded the interior as well which includes making it quieter. The driver gets a 10 way adjustable seat. The folks in the front also get seats that heat or cool (especially nice for an Arizona summer).

My test car had the Advance package that includes two large displays in the center of the dash. If you’re a technophobe I can tell you right now you’ll find it intimidating. If you’re up for advanced controls, the Acura gives you all kinds of options and adjustments. You can also get an exceptionally wide-angle display that drops from the roof and will make everyone in the back happy. Speaking of the back, the MDX also has a third row seat which means it can seat seven people. From from experience, I can tell you that even though you might not use it much, it can be very handy to have.

The MDX has plenty of modern safety features. It has a Lane Keeping Assist System that warns you when you’re drifting. Adaptive Cruise Control is another asset. It doesn’t just warn you that you’re coming up on a slower car, but it puts on the brakes as well. You can also determine how close you want to follow before it begins to slow. Both were pretty unobtrusive and the whole system works well.

While I like the looks of the MDX, I can’t say I love it. Acura has worked hard to give the grill an angular look that I’m sure some people love. I like the subtle body changes. The side has a gentle concave that takes away the slab look, and the back has a more rounded feel. But if you’re looking for a curvy car, the MDX is not it.

My test car came in at $57,400, but the 2014 MDX starts at around $43,000. That’s $990 less than last year. I like the fact that it has a four-year/50,000 mile warranty.

About the only thing I didn’t like about the 2014 Acura MDX is that it requires premium fuel. That helps with the mileage but hurts the checking account every time you fill up. But then, this is a luxury car.

I think old MDX owners are going to love the new version. Acura took a good car and made it better. You can’t ask for much more than that.