Infiniti, the upper echelon of Nissan, has competed, punch for punch with Lexus, the upper echelon of Toyota, over the 16 years since they were invented for and marketed in the United States. But Infiniti has never achieved the popularity and sales of the Lexus. And competition in the mid-size luxury segment is fierce, featuring quality automobiles from Acura, Jaguar, Mercedes, BMW, Cadillac, Audi and more.

In this market auto manufacturers struggle to invent new gimmicks to separate these $50,000 cars from perfectly competent and well equipped $25,000 cars that also come, for example, with navigation systems. The Infiniti M35 is no exception.

One system we found helpful was the auto sensing cruise control. Traveling to Los Angeles is difficult to do using a normal cruise control system due to heavy traffic and changes in speed. The Infiniti system, however, works fine. Its forward radar uses throttle and brake management to both maintain speed and keep the car a specific distance behind the vehicle in front, regardless of your cruise speed setting. If a driver cuts in front of the M35x, the brakes quickly slow the car until the requisite gap is achieved.

Infiniti’s M35 is ideal for drivers and passengers longing for a feeling of isolation and safety on long journeys.

The premium Bose Studio Surround Sound system was the best heard in our nearly 10 years of reviewing cars for Road Test. With 16 speakers, four in the top of the front seats just below your ears, and some special sound manipulation, it has to be heard to be believed.

The heated and cooled seats should become a must for all cars - this is the only way to temperature control your body. In San Diego’s climate, these cooling seats will have you driving around in your car all day on a hot summer’s day.

Add to these systems electronic brake distribution, suspension stability, all-wheel drive, a limited slip rear axle and a 3.5 liter V-6, 280 hp engine with 5-speed automatic transmission and you have a capable all around luxury car.

The M35x’s ride is what one expects in a luxmobile, very relaxing with competent handling. The steering is a little heavier than in the BMW 5 series, which gives one the perception that the Infiniti is less of a driver’s car.

For long journeys with all the luxury gimmicks anyone could want, a relaxing ride, and a feeling of isolation and safety, this car is hard to beat.

A recent 100-mile journey left us very fresh with no tension or backache.

Five trim levels are available: M35, (V-6, rear wheel drive, base price $40,480); M35 Sport, (V-6, rear wheel drive, rear active steering and 19-inch wheels, base price $43,640); M35x AWD (V-6 and all wheel drive, base price $43,340, as tested $49,000); M45 (V-8 with rear wheel drive, base price $47,150); and M45 Sport (V-8 with rear wheel drive, rear active steering and 19-inch wheels, base price $49,950).

The exterior appearance is pleasant but generic, much like many Japanese and American cars on the road today. The interior is beautiful, pure luxury exudes from the leather, wood and cushy but firm seats.

The car has a few quirks, in particular the start procedure. With a key in your possession, starting the engine is as simple as putting a foot on the brake and pressing the “start” button. Push start again and the engine stops. On one occasion this tester forgot that a change of pants had occurred and jumped in the car which, without the key in pocket, of course would not start.

A tiny rear camera gives a full view of what’s behind the car when reverse is selected. The right hand mirror also looks down at the curb, which is sometimes helpful. A lane departure warning system, which beep-beeps when you wander over a divider strip, is a little irritating at times.

The EPA fuel consumption estimate is 17 city/24 highway with the 4-wheel drive tested, and 18 city/25 highway with the 2 wheel drive. Unfortunately expensive premium fuel is recommended.

The warranty is 48 months or 60,000 miles with a power train warranty of 72 months or 70,000 miles.

With this car, Nissan is working very hard for your approval. With Consumer Reports rating it higher than the hallowed Lexus GS and BMW 5 series, it clearly is a hot car. On the Internet msnautos.com reader/owners rate it a 94 out of 100.

With its new M series, Infiniti may finally be able to compete with the big boys on an even plane.

Motoring since 1952, Austin Lynas has owned 55 cars and at one time raced mini-sedans in England. An aerospace engineer, he was instrumental in developing the anti-skid systems used in British military aircraft that preceded today’s ABS systems. Lynas can be reached by e-mail at austin@sandiegometro.com.