Lexus' new turbocharged engine may not save customers gas money

Lexus is about to introduce a new compact crossover with a turbocharged engine. Here's why it might not save its customers money at the pump.

There is exciting news from Lexus. The company is going to launch its new RAV 4 sized NX crossover late this year and the company has confirmed it will be the first Lexus with a modern, four cylinder turbocharged engine. Equally exciting, is that management officials have said the new engine will spread throughout the Toyota family. That is great because some of the Toyota vehicles are saddled with aging engines way overdue for an update. The Tacoma would benefit from a new engine for example. We have one major worry however.

We are concerned that the new NX 250 Turbo, as we are calling it, will require premium fuel, which costs about 10% more than regular unleaded. Our analysis shows that if this is the case, the new Lexus crossover will have no better fuel economy than if if Lexus had used the existing V6. In the 2012 Toyota RAV 4 that engine delivered 22 MPG combined and 26 MPG highway with an old fashioned 4 speed transmission. With a 6 speed it would have had about 24 MPG combined. That is only 1 MPG less than the new RAV 4 gets with its weak, non-turbo, 4-cylinder.

In the Lexus family there are presently two workhorse engines. Both use the same basic V6 architecture and displace 3.5 liters. In the ES 350 and also the RX 350 the engine uses fuel injection and is mounted in the engine bay left to right (transversely mounted.). The engine provides adequate power, and even with just a 6 speed transmission it delivers class average fuel economy. Lexus approves the use of regular unleaded gasoline in this engine in these cars and they are the two top sellers in the Lexus line by far.

The higher power version of that engine is mounted front to back (longitudinally) and uses both direct and also port fuel injection to balance low speed drivability and high rev power. This engine, when found in the new Lexus IS 350, is a class leader with 306 horsepower, but it requires premium unleaded for a couple of reasons. The main reason is so the engine can make the most possible power, but Lexus also knows that the engine needs the added detergent found in premium fuel to operate properly over the long run.

If Lexus introduces the new NX 250 Turbo with a turbocharged 4 cylinder and requires premium fuel we will have to say that the company has not moved the needle for its customers that want a responsive engine that is fuel economical.

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